summaryrefslogtreecommitdiffstats
path: root/src/smtp/smtp.c
blob: 51b2e6dba67aa0b70d2788523b0a1b13d63ee83a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
/*++
/* NAME
/*	smtp, lmtp 8
/* SUMMARY
/*	Postfix SMTP+LMTP client
/* SYNOPSIS
/*	\fBsmtp\fR [generic Postfix daemon options] [flags=DORX]
/*
/*	\fBlmtp\fR [generic Postfix daemon options] [flags=DORX]
/* DESCRIPTION
/*	The Postfix SMTP+LMTP client implements the SMTP and LMTP mail
/*	delivery protocols. It processes message delivery requests from
/*	the queue manager. Each request specifies a queue file, a sender
/*	address, a domain or host to deliver to, and recipient information.
/*	This program expects to be run from the \fBmaster\fR(8) process
/*	manager. The process name, \fBsmtp\fR or \fBlmtp\fR, controls
/*	the protocol, and the names of the configuration parameters
/*	that will be used.
/*
/*	The SMTP+LMTP client updates the queue file and marks recipients
/*	as finished, or it informs the queue manager that delivery should
/*	be tried again at a later time. Delivery status reports are sent
/*	to the \fBbounce\fR(8), \fBdefer\fR(8) or \fBtrace\fR(8) daemon as
/*	appropriate.
/*
/*	The server lookup strategy is different for SMTP and LMTP,
/*	as described in the sections "SMTP SERVER LOOKUP" and "LMTP
/*	SERVER LOOKUP".
/*
/*	After a successful mail transaction, a connection may be saved
/*	to the \fBscache\fR(8) connection cache server, so that it
/*	may be used by any SMTP+LMTP client for a subsequent transaction.
/*
/*	By default, connection caching is enabled temporarily for
/*	destinations that have a high volume of mail in the active
/*	queue. Connection caching can be enabled permanently for
/*	specific destinations.
/* SMTP SERVER LOOKUP
/* .ad
/* .fi
/*	The Postfix SMTP client supports multiple destinations
/*	separated by comma or whitespace (Postfix 3.5 and later).
/*	Each destination is tried in the specified order.
/*
/*	SMTP destinations have the following form:
/* .IP \fIdomainname\fR
/* .IP \fIdomainname\fR:\fIservice\fR
/*	Look up the mail exchangers for the specified domain, and
/*	connect to the specified service (default: \fBsmtp\fR).
/*	Optionally, mail exchangers may be looked up with SRV queries
/*	instead of MX; this requires that \fIservice\fR is given
/*	in symbolic form.
/* .IP [\fIhostname\fR]
/* .IP [\fIhostname\fR]:\fIservice\fR
/*	Look up the address(es) for the specified host, and connect to
/*	the specified service (default: \fBsmtp\fR).
/* .IP [\fIaddress\fR]
/* .IP [\fIaddress\fR]:\fIservice\fR
/*	Connect to the host at the specified address, and connect
/*	to the specified service (default: \fBsmtp\fR). An IPv6 address
/*	must be formatted as [\fBipv6\fR:\fIaddress\fR].
/* LMTP SERVER LOOKUP
/* .ad
/* .fi
/*	The Postfix LMTP client supports multiple destinations
/*	separated by comma or whitespace (Postfix 3.5 and later).
/*	Each destination is tried in the specified order.
/*
/*	LMTP destinations have the following form:
/* .IP \fBunix\fR:\fIpathname\fR
/*	Connect to the local UNIX-domain server that is bound to the specified
/*	\fIpathname\fR. If the process runs chrooted, an absolute pathname
/*	is interpreted relative to the Postfix queue directory.
/* .IP \fBinet\fR:\fIdomainname\fR
/* .IP \fBinet\fR:\fIdomainname\fR:\fIservice\fR
/*	Look up the LMTP servers for the specified domain and service
/*	(default: \fBlmtp\fR).
/*	This form is supported when SRV lookups are enabled, and
/*	requires that \fIservice\fR is in symbolic form.
/* .IP \fBinet\fR:\fIhostname\fR
/* .IP \fBinet\fR:\fIhostname\fR:\fIservice\fR
/*	Look up the address(es) for the specified host, and connect to
/*	the specified service (default: \fBlmtp\fR). When SRV lookups
/*	are enabled, use the form \fB[\fIhostname\fB]\fR to force
/*	address lookups.
/* .IP \fBinet\fR:[\fIaddress\fR]
/* .IP \fBinet\fR:[\fIaddress\fR]:\fIservice\fR
/*	Connect to the specified local or remote host and service
/*	(default: \fBlmtp\fR).
/*	An IPv6 address must be formatted as [\fBipv6\fR:\fIaddress\fR].
/* SINGLE-RECIPIENT DELIVERY
/* .ad
/* .fi
/*	By default, the Postfix SMTP+LMTP client delivers mail to
/*	multiple recipients per delivery request. This is undesirable
/*	when prepending a \fBDelivered-to:\fR or \fBX-Original-To:\fR
/*	message header. To prevent Postfix from sending multiple
/*	recipients per delivery request, specify
/* .sp
/* .nf
/*	    \fItransport\fB_destination_recipient_limit = 1\fR
/* .fi
/*
/*	in the Postfix \fBmain.cf\fR file, where \fItransport\fR
/*	is the name in the first column of the Postfix \fBmaster.cf\fR
/*	entry for this mail delivery service.
/* COMMAND ATTRIBUTE SYNTAX
/* .ad
/* .fi
/* .IP "\fBflags=DORX\fR (optional)"
/*	Optional message processing flags.
/* .RS
/* .IP \fBD\fR
/*	Prepend a "\fBDelivered-To: \fIrecipient\fR" message header
/*	with the envelope recipient address. Note: for this to work,
/*	the \fItransport\fB_destination_recipient_limit\fR must be
/*	1 (see SINGLE-RECIPIENT DELIVERY above for details).
/* .sp
/*	The \fBD\fR flag also enforces loop detection: if a message
/*	already contains a \fBDelivered-To:\fR header with the same
/*	recipient address, then the message is returned as
/*	undeliverable. The address comparison is case insensitive.
/* .sp
/*	This feature is available as of Postfix 3.5.
/* .IP \fBO\fR
/*	Prepend an "\fBX-Original-To: \fIrecipient\fR" message
/*	header with the recipient address as given to Postfix. Note:
/*	for this to work, the
/*	\fItransport\fB_destination_recipient_limit\fR must be 1
/*	(see SINGLE-RECIPIENT DELIVERY above for details).
/* .sp
/*	This feature is available as of Postfix 3.5.
/* .IP \fBR\fR
/*	Prepend a "\fBReturn-Path: <\fIsender\fB>\fR" message header
/*	with the envelope sender address.
/* .sp
/*	This feature is available as of Postfix 3.5.
/* .IP \fBX\fR
/*	Indicates that the delivery is final. This flag affects
/*	the status reported in "success" DSN (delivery status
/*	notification) messages, and changes it from "relayed" into
/*	"delivered".
/* .sp
/*	This feature is available as of Postfix 3.5.
/* .RE
/* SECURITY
/* .ad
/* .fi
/*	The SMTP+LMTP client is moderately security-sensitive. It
/*	talks to SMTP or LMTP servers and to DNS servers on the
/*	network. The SMTP+LMTP client can be run chrooted at fixed
/*	low privilege.
/* STANDARDS
/*	RFC 821 (SMTP protocol)
/*	RFC 822 (ARPA Internet Text Messages)
/*	RFC 1651 (SMTP service extensions)
/*	RFC 1652 (8bit-MIME transport)
/*	RFC 1870 (Message Size Declaration)
/*	RFC 2033 (LMTP protocol)
/*	RFC 2034 (SMTP Enhanced Error Codes)
/*	RFC 2045 (MIME: Format of Internet Message Bodies)
/*	RFC 2046 (MIME: Media Types)
/*	RFC 2554 (AUTH command)
/*	RFC 2821 (SMTP protocol)
/*	RFC 2782 (SRV resource records)
/*	RFC 2920 (SMTP Pipelining)
/*	RFC 3207 (STARTTLS command)
/*	RFC 3461 (SMTP DSN Extension)
/*	RFC 3463 (Enhanced Status Codes)
/*	RFC 4954 (AUTH command)
/*	RFC 5321 (SMTP protocol)
/*	RFC 6531 (Internationalized SMTP)
/*	RFC 6533 (Internationalized Delivery Status Notifications)
/*	RFC 7672 (SMTP security via opportunistic DANE TLS)
/* DIAGNOSTICS
/*	Problems and transactions are logged to \fBsyslogd\fR(8)
/*	or \fBpostlogd\fR(8).
/*	Corrupted message files are marked so that the queue manager can
/*	move them to the \fBcorrupt\fR queue for further inspection.
/*
/*	Depending on the setting of the \fBnotify_classes\fR parameter,
/*	the postmaster is notified of bounces, protocol problems, and of
/*	other trouble.
/* BUGS
/*	SMTP and LMTP connection reuse for TLS (without closing the
/*	SMTP or LMTP connection) is not supported before Postfix 3.4.
/*
/*	SMTP and LMTP connection reuse assumes that SASL credentials
/*	are valid for all destinations that map onto the same IP
/*	address and TCP port.
/* CONFIGURATION PARAMETERS
/* .ad
/* .fi
/*	Postfix versions 2.3 and later implement the SMTP and LMTP
/*	client with the same program, and choose the protocol and
/*	configuration parameters based on the process name, \fBsmtp\fR
/*	or \fBlmtp\fR.
/*
/*	Most smtp_\fIxxx\fR configuration parameters have an
/*	lmtp_\fIxxx\fR "mirror" parameter for the equivalent LMTP
/*	feature. This document describes only those LMTP-related
/*	parameters that aren't simply "mirror" parameters.
/*
/*	Changes to \fBmain.cf\fR are picked up automatically, as \fBsmtp\fR(8)
/*	processes run for only a limited amount of time. Use the command
/*	"\fBpostfix reload\fR" to speed up a change.
/*
/*	The text below provides only a parameter summary. See
/*	\fBpostconf\fR(5) for more details including examples.
/* COMPATIBILITY CONTROLS
/* .ad
/* .fi
/* .IP "\fBignore_mx_lookup_error (no)\fR"
/*	Ignore DNS MX lookups that produce no response.
/* .IP "\fBsmtp_always_send_ehlo (yes)\fR"
/*	Always send EHLO at the start of an SMTP session.
/* .IP "\fBsmtp_never_send_ehlo (no)\fR"
/*	Never send EHLO at the start of an SMTP session.
/* .IP "\fBsmtp_defer_if_no_mx_address_found (no)\fR"
/*	Defer mail delivery when no MX record resolves to an IP address.
/* .IP "\fBsmtp_line_length_limit (998)\fR"
/*	The maximal length of message header and body lines that Postfix
/*	will send via SMTP.
/* .IP "\fBsmtp_pix_workaround_delay_time (10s)\fR"
/*	How long the Postfix SMTP client pauses before sending
/*	".<CR><LF>" in order to work around the PIX firewall
/*	"<CR><LF>.<CR><LF>" bug.
/* .IP "\fBsmtp_pix_workaround_threshold_time (500s)\fR"
/*	How long a message must be queued before the Postfix SMTP client
/*	turns on the PIX firewall "<CR><LF>.<CR><LF>"
/*	bug workaround for delivery through firewalls with "smtp fixup"
/*	mode turned on.
/* .IP "\fBsmtp_pix_workarounds (disable_esmtp, delay_dotcrlf)\fR"
/*	A list that specifies zero or more workarounds for CISCO PIX
/*	firewall bugs.
/* .IP "\fBsmtp_pix_workaround_maps (empty)\fR"
/*	Lookup tables, indexed by the remote SMTP server address, with
/*	per-destination workarounds for CISCO PIX firewall bugs.
/* .IP "\fBsmtp_quote_rfc821_envelope (yes)\fR"
/*	Quote addresses in Postfix SMTP client MAIL FROM and RCPT TO commands
/*	as required
/*	by RFC 5321.
/* .IP "\fBsmtp_reply_filter (empty)\fR"
/*	A mechanism to transform replies from remote SMTP servers one
/*	line at a time.
/* .IP "\fBsmtp_skip_5xx_greeting (yes)\fR"
/*	Skip remote SMTP servers that greet with a 5XX status code.
/* .IP "\fBsmtp_skip_quit_response (yes)\fR"
/*	Do not wait for the response to the SMTP QUIT command.
/* .PP
/*	Available in Postfix version 2.0 and earlier:
/* .IP "\fBsmtp_skip_4xx_greeting (yes)\fR"
/*	Skip SMTP servers that greet with a 4XX status code (go away, try
/*	again later).
/* .PP
/*	Available in Postfix version 2.2 and later:
/* .IP "\fBsmtp_discard_ehlo_keyword_address_maps (empty)\fR"
/*	Lookup tables, indexed by the remote SMTP server address, with
/*	case insensitive lists of EHLO keywords (pipelining, starttls, auth,
/*	etc.) that the Postfix SMTP client will ignore in the EHLO response from a
/*	remote SMTP server.
/* .IP "\fBsmtp_discard_ehlo_keywords (empty)\fR"
/*	A case insensitive list of EHLO keywords (pipelining, starttls,
/*	auth, etc.) that the Postfix SMTP client will ignore in the EHLO
/*	response from a remote SMTP server.
/* .IP "\fBsmtp_generic_maps (empty)\fR"
/*	Optional lookup tables that perform address rewriting in the
/*	Postfix SMTP client, typically to transform a locally valid address into
/*	a globally valid address when sending mail across the Internet.
/* .PP
/*	Available in Postfix version 2.2.9 and later:
/* .IP "\fBsmtp_cname_overrides_servername (version dependent)\fR"
/*	When the remote SMTP servername is a DNS CNAME, replace the
/*	servername with the result from CNAME expansion for the purpose of
/*	logging, SASL password lookup, TLS
/*	policy decisions, or TLS certificate verification.
/* .PP
/*	Available in Postfix version 2.3 and later:
/* .IP "\fBlmtp_discard_lhlo_keyword_address_maps (empty)\fR"
/*	Lookup tables, indexed by the remote LMTP server address, with
/*	case insensitive lists of LHLO keywords (pipelining, starttls,
/*	auth, etc.) that the Postfix LMTP client will ignore in the LHLO
/*	response
/*	from a remote LMTP server.
/* .IP "\fBlmtp_discard_lhlo_keywords (empty)\fR"
/*	A case insensitive list of LHLO keywords (pipelining, starttls,
/*	auth, etc.) that the Postfix LMTP client will ignore in the LHLO
/*	response
/*	from a remote LMTP server.
/* .PP
/*	Available in Postfix version 2.4.4 and later:
/* .IP "\fBsend_cyrus_sasl_authzid (no)\fR"
/*	When authenticating to a remote SMTP or LMTP server with the
/*	default setting "no", send no SASL authoriZation ID (authzid); send
/*	only the SASL authentiCation ID (authcid) plus the authcid's password.
/* .PP
/*	Available in Postfix version 2.5 and later:
/* .IP "\fBsmtp_header_checks (empty)\fR"
/*	Restricted \fBheader_checks\fR(5) tables for the Postfix SMTP client.
/* .IP "\fBsmtp_mime_header_checks (empty)\fR"
/*	Restricted \fBmime_header_checks\fR(5) tables for the Postfix SMTP
/*	client.
/* .IP "\fBsmtp_nested_header_checks (empty)\fR"
/*	Restricted \fBnested_header_checks\fR(5) tables for the Postfix SMTP
/*	client.
/* .IP "\fBsmtp_body_checks (empty)\fR"
/*	Restricted \fBbody_checks\fR(5) tables for the Postfix SMTP client.
/* .PP
/*	Available in Postfix version 2.6 and later:
/* .IP "\fBtcp_windowsize (0)\fR"
/*	An optional workaround for routers that break TCP window scaling.
/* .PP
/*	Available in Postfix version 2.8 and later:
/* .IP "\fBsmtp_dns_resolver_options (empty)\fR"
/*	DNS Resolver options for the Postfix SMTP client.
/* .PP
/*	Available in Postfix version 2.9 - 3.6:
/* .IP "\fBsmtp_per_record_deadline (no)\fR"
/*	Change the behavior of the smtp_*_timeout time limits, from a
/*	time limit per read or write system call, to a time limit to send
/*	or receive a complete record (an SMTP command line, SMTP response
/*	line, SMTP message content line, or TLS protocol message).
/* .PP
/*	Available in Postfix version 2.9 and later:
/* .IP "\fBsmtp_send_dummy_mail_auth (no)\fR"
/*	Whether or not to append the "AUTH=<>" option to the MAIL
/*	FROM command in SASL-authenticated SMTP sessions.
/* .PP
/*	Available in Postfix version 2.11 and later:
/* .IP "\fBsmtp_dns_support_level (empty)\fR"
/*	Level of DNS support in the Postfix SMTP client.
/* .PP
/*	Available in Postfix version 3.0 and later:
/* .IP "\fBsmtp_delivery_status_filter ($default_delivery_status_filter)\fR"
/*	Optional filter for the \fBsmtp\fR(8) delivery agent to change the
/*	delivery status code or explanatory text of successful or unsuccessful
/*	deliveries.
/* .IP "\fBsmtp_dns_reply_filter (empty)\fR"
/*	Optional filter for Postfix SMTP client DNS lookup results.
/* .PP
/*	Available in Postfix version 3.3 and later:
/* .IP "\fBsmtp_balance_inet_protocols (yes)\fR"
/*	When a remote destination resolves to a combination of IPv4 and
/*	IPv6 addresses, ensure that the Postfix SMTP client can try both
/*	address types before it runs into the smtp_mx_address_limit.
/* .PP
/*	Available in Postfix 3.5 and later:
/* .IP "\fBinfo_log_address_format (external)\fR"
/*	The email address form that will be used in non-debug logging
/*	(info, warning, etc.).
/* .PP
/*	Available in Postfix 3.6 and later:
/* .IP "\fBdnssec_probe (ns:.)\fR"
/*	The DNS query type (default: "ns") and DNS query name (default:
/*	".") that Postfix may use to determine whether DNSSEC validation
/*	is available.
/* .IP "\fBknown_tcp_ports (lmtp=24, smtp=25, smtps=submissions=465, submission=587)\fR"
/*	Optional setting that avoids lookups in the \fBservices\fR(5) database.
/* .PP
/*	Available in Postfix version 3.7 and later:
/* .IP "\fBsmtp_per_request_deadline (no)\fR"
/*	Change the behavior of the smtp_*_timeout time limits, from a
/*	time limit per plaintext or TLS read or write call, to a combined
/*	time limit for sending a complete SMTP request and for receiving a
/*	complete SMTP response.
/* .IP "\fBsmtp_min_data_rate (500)\fR"
/*	The minimum plaintext data transfer rate in bytes/second for
/*	DATA requests, when deadlines are enabled with smtp_per_request_deadline.
/* .IP "\fBheader_from_format (standard)\fR"
/*	The format of the Postfix-generated \fBFrom:\fR header.
/* .PP
/*	Available in Postfix version 3.8 and later:
/* .IP "\fBuse_srv_lookup (empty)\fR"
/*	Enables discovery for the specified service(s) using DNS SRV
/*	records.
/* .IP "\fBignore_srv_lookup_error (no)\fR"
/*	When SRV record lookup fails, fall back to MX or IP address
/*	lookup as if SRV record lookup was not enabled.
/* .IP "\fBallow_srv_lookup_fallback (no)\fR"
/*	When SRV record lookup fails or no SRV record exists, fall back
/*	to MX or IP address lookup as if SRV record lookup was not enabled.
/* MIME PROCESSING CONTROLS
/* .ad
/* .fi
/*	Available in Postfix version 2.0 and later:
/* .IP "\fBdisable_mime_output_conversion (no)\fR"
/*	Disable the conversion of 8BITMIME format to 7BIT format.
/* .IP "\fBmime_boundary_length_limit (2048)\fR"
/*	The maximal length of MIME multipart boundary strings.
/* .IP "\fBmime_nesting_limit (100)\fR"
/*	The maximal recursion level that the MIME processor will handle.
/* EXTERNAL CONTENT INSPECTION CONTROLS
/* .ad
/* .fi
/*	Available in Postfix version 2.1 and later:
/* .IP "\fBsmtp_send_xforward_command (no)\fR"
/*	Send the non-standard XFORWARD command when the Postfix SMTP server
/*	EHLO response announces XFORWARD support.
/* SASL AUTHENTICATION CONTROLS
/* .ad
/* .fi
/* .IP "\fBsmtp_sasl_auth_enable (no)\fR"
/*	Enable SASL authentication in the Postfix SMTP client.
/* .IP "\fBsmtp_sasl_password_maps (empty)\fR"
/*	Optional Postfix SMTP client lookup tables with one username:password
/*	entry per sender, remote hostname or next-hop domain.
/* .IP "\fBsmtp_sasl_security_options (noplaintext, noanonymous)\fR"
/*	Postfix SMTP client SASL security options; as of Postfix 2.3
/*	the list of available
/*	features depends on the SASL client implementation that is selected
/*	with \fBsmtp_sasl_type\fR.
/* .PP
/*	Available in Postfix version 2.2 and later:
/* .IP "\fBsmtp_sasl_mechanism_filter (empty)\fR"
/*	If non-empty, a Postfix SMTP client filter for the remote SMTP
/*	server's list of offered SASL mechanisms.
/* .PP
/*	Available in Postfix version 2.3 and later:
/* .IP "\fBsmtp_sender_dependent_authentication (no)\fR"
/*	Enable sender-dependent authentication in the Postfix SMTP client; this is
/*	available only with SASL authentication, and disables SMTP connection
/*	caching to ensure that mail from different senders will use the
/*	appropriate credentials.
/* .IP "\fBsmtp_sasl_path (empty)\fR"
/*	Implementation-specific information that the Postfix SMTP client
/*	passes through to
/*	the SASL plug-in implementation that is selected with
/*	\fBsmtp_sasl_type\fR.
/* .IP "\fBsmtp_sasl_type (cyrus)\fR"
/*	The SASL plug-in type that the Postfix SMTP client should use
/*	for authentication.
/* .PP
/*	Available in Postfix version 2.5 and later:
/* .IP "\fBsmtp_sasl_auth_cache_name (empty)\fR"
/*	An optional table to prevent repeated SASL authentication
/*	failures with the same remote SMTP server hostname, username and
/*	password.
/* .IP "\fBsmtp_sasl_auth_cache_time (90d)\fR"
/*	The maximal age of an smtp_sasl_auth_cache_name entry before it
/*	is removed.
/* .IP "\fBsmtp_sasl_auth_soft_bounce (yes)\fR"
/*	When a remote SMTP server rejects a SASL authentication request
/*	with a 535 reply code, defer mail delivery instead of returning
/*	mail as undeliverable.
/* .PP
/*	Available in Postfix version 2.9 and later:
/* .IP "\fBsmtp_send_dummy_mail_auth (no)\fR"
/*	Whether or not to append the "AUTH=<>" option to the MAIL
/*	FROM command in SASL-authenticated SMTP sessions.
/* .PP
/*	Available in Postfix version 3.9 and later:
/* .IP "\fBsmtp_sasl_password_result_delimiter (:)\fR"
/*	The delimiter between username and password in sasl_passwd_maps lookup
/*	results.
/* STARTTLS SUPPORT CONTROLS
/* .ad
/* .fi
/*	Detailed information about STARTTLS configuration may be found
/*	in the TLS_README document.
/* .IP "\fBsmtp_tls_security_level (empty)\fR"
/*	The default SMTP TLS security level for the Postfix SMTP client.
/* .IP "\fBsmtp_sasl_tls_security_options ($smtp_sasl_security_options)\fR"
/*	The SASL authentication security options that the Postfix SMTP
/*	client uses for TLS encrypted SMTP sessions.
/* .IP "\fBsmtp_starttls_timeout (300s)\fR"
/*	Time limit for Postfix SMTP client write and read operations
/*	during TLS startup and shutdown handshake procedures.
/* .IP "\fBsmtp_tls_CAfile (empty)\fR"
/*	A file containing CA certificates of root CAs trusted to sign
/*	either remote SMTP server certificates or intermediate CA certificates.
/* .IP "\fBsmtp_tls_CApath (empty)\fR"
/*	Directory with PEM format Certification Authority certificates
/*	that the Postfix SMTP client uses to verify a remote SMTP server
/*	certificate.
/* .IP "\fBsmtp_tls_cert_file (empty)\fR"
/*	File with the Postfix SMTP client RSA certificate in PEM format.
/* .IP "\fBsmtp_tls_mandatory_ciphers (medium)\fR"
/*	The minimum TLS cipher grade that the Postfix SMTP client will
/*	use with
/*	mandatory TLS encryption.
/* .IP "\fBsmtp_tls_exclude_ciphers (empty)\fR"
/*	List of ciphers or cipher types to exclude from the Postfix
/*	SMTP client cipher
/*	list at all TLS security levels.
/* .IP "\fBsmtp_tls_mandatory_exclude_ciphers (empty)\fR"
/*	Additional list of ciphers or cipher types to exclude from the
/*	Postfix SMTP client cipher list at mandatory TLS security levels.
/* .IP "\fBsmtp_tls_dcert_file (empty)\fR"
/*	File with the Postfix SMTP client DSA certificate in PEM format.
/* .IP "\fBsmtp_tls_dkey_file ($smtp_tls_dcert_file)\fR"
/*	File with the Postfix SMTP client DSA private key in PEM format.
/* .IP "\fBsmtp_tls_key_file ($smtp_tls_cert_file)\fR"
/*	File with the Postfix SMTP client RSA private key in PEM format.
/* .IP "\fBsmtp_tls_loglevel (0)\fR"
/*	Enable additional Postfix SMTP client logging of TLS activity.
/* .IP "\fBsmtp_tls_note_starttls_offer (no)\fR"
/*	Log the hostname of a remote SMTP server that offers STARTTLS,
/*	when TLS is not already enabled for that server.
/* .IP "\fBsmtp_tls_policy_maps (empty)\fR"
/*	Optional lookup tables with the Postfix SMTP client TLS security
/*	policy by next-hop destination; when a non-empty value is specified,
/*	this overrides the obsolete smtp_tls_per_site parameter.
/* .IP "\fBsmtp_tls_mandatory_protocols (see 'postconf -d' output)\fR"
/*	TLS protocols that the Postfix SMTP client will use with mandatory
/*	TLS encryption.
/* .IP "\fBsmtp_tls_scert_verifydepth (9)\fR"
/*	The verification depth for remote SMTP server certificates.
/* .IP "\fBsmtp_tls_secure_cert_match (nexthop, dot-nexthop)\fR"
/*	How the Postfix SMTP client verifies the server certificate
/*	peername for the "secure" TLS security level.
/* .IP "\fBsmtp_tls_session_cache_database (empty)\fR"
/*	Name of the file containing the optional Postfix SMTP client
/*	TLS session cache.
/* .IP "\fBsmtp_tls_session_cache_timeout (3600s)\fR"
/*	The expiration time of Postfix SMTP client TLS session cache
/*	information.
/* .IP "\fBsmtp_tls_verify_cert_match (hostname)\fR"
/*	How the Postfix SMTP client verifies the server certificate
/*	peername for the
/*	"verify" TLS security level.
/* .IP "\fBtls_daemon_random_bytes (32)\fR"
/*	The number of pseudo-random bytes that an \fBsmtp\fR(8) or \fBsmtpd\fR(8)
/*	process requests from the \fBtlsmgr\fR(8) server in order to seed its
/*	internal pseudo random number generator (PRNG).
/* .IP "\fBtls_high_cipherlist (see 'postconf -d' output)\fR"
/*	The OpenSSL cipherlist for "high" grade ciphers.
/* .IP "\fBtls_medium_cipherlist (see 'postconf -d' output)\fR"
/*	The OpenSSL cipherlist for "medium" or higher grade ciphers.
/* .IP "\fBtls_null_cipherlist (eNULL:!aNULL)\fR"
/*	The OpenSSL cipherlist for "NULL" grade ciphers that provide
/*	authentication without encryption.
/* .PP
/*	Available in in Postfix version 2.3..3.7:
/* .IP "\fBtls_low_cipherlist (see 'postconf -d' output)\fR"
/*	The OpenSSL cipherlist for "low" or higher grade ciphers.
/* .IP "\fBtls_export_cipherlist (see 'postconf -d' output)\fR"
/*	The OpenSSL cipherlist for "export" or higher grade ciphers.
/* .PP
/*	Available in Postfix version 2.4 and later:
/* .IP "\fBsmtp_sasl_tls_verified_security_options ($smtp_sasl_tls_security_options)\fR"
/*	The SASL authentication security options that the Postfix SMTP
/*	client uses for TLS encrypted SMTP sessions with a verified server
/*	certificate.
/* .PP
/*	Available in Postfix version 2.5 and later:
/* .IP "\fBsmtp_tls_fingerprint_cert_match (empty)\fR"
/*	List of acceptable remote SMTP server certificate fingerprints for
/*	the "fingerprint" TLS security level (\fBsmtp_tls_security_level\fR =
/*	fingerprint).
/* .IP "\fBsmtp_tls_fingerprint_digest (see 'postconf -d' output)\fR"
/*	The message digest algorithm used to construct remote SMTP server
/*	certificate fingerprints.
/* .PP
/*	Available in Postfix version 2.6 and later:
/* .IP "\fBsmtp_tls_protocols (see 'postconf -d' output)\fR"
/*	TLS protocols that the Postfix SMTP client will use with
/*	opportunistic TLS encryption.
/* .IP "\fBsmtp_tls_ciphers (medium)\fR"
/*	The minimum TLS cipher grade that the Postfix SMTP client
/*	will use with opportunistic TLS encryption.
/* .IP "\fBsmtp_tls_eccert_file (empty)\fR"
/*	File with the Postfix SMTP client ECDSA certificate in PEM format.
/* .IP "\fBsmtp_tls_eckey_file ($smtp_tls_eccert_file)\fR"
/*	File with the Postfix SMTP client ECDSA private key in PEM format.
/* .PP
/*	Available in Postfix version 2.7 and later:
/* .IP "\fBsmtp_tls_block_early_mail_reply (no)\fR"
/*	Try to detect a mail hijacking attack based on a TLS protocol
/*	vulnerability (CVE-2009-3555), where an attacker prepends malicious
/*	HELO, MAIL, RCPT, DATA commands to a Postfix SMTP client TLS session.
/* .PP
/*	Available in Postfix version 2.8 and later:
/* .IP "\fBtls_disable_workarounds (see 'postconf -d' output)\fR"
/*	List or bit-mask of OpenSSL bug work-arounds to disable.
/* .PP
/*	Available in Postfix version 2.11-3.1:
/* .IP "\fBtls_dane_digest_agility (on)\fR"
/*	Configure RFC7671 DANE TLSA digest algorithm agility.
/* .IP "\fBtls_dane_trust_anchor_digest_enable (yes)\fR"
/*	Enable support for RFC 6698 (DANE TLSA) DNS records that contain
/*	digests of trust-anchors with certificate usage "2".
/* .PP
/*	Available in Postfix version 2.11 and later:
/* .IP "\fBsmtp_tls_trust_anchor_file (empty)\fR"
/*	Zero or more PEM-format files with trust-anchor certificates
/*	and/or public keys.
/* .IP "\fBsmtp_tls_force_insecure_host_tlsa_lookup (no)\fR"
/*	Lookup the associated DANE TLSA RRset even when a hostname is
/*	not an alias and its address records lie in an unsigned zone.
/* .IP "\fBtlsmgr_service_name (tlsmgr)\fR"
/*	The name of the \fBtlsmgr\fR(8) service entry in master.cf.
/* .PP
/*	Available in Postfix version 3.0 and later:
/* .IP "\fBsmtp_tls_wrappermode (no)\fR"
/*	Request that the Postfix SMTP client connects using the
/*	SUBMISSIONS/SMTPS protocol instead of using the STARTTLS command.
/* .PP
/*	Available in Postfix version 3.1 and later:
/* .IP "\fBsmtp_tls_dane_insecure_mx_policy (see 'postconf -d' output)\fR"
/*	The TLS policy for MX hosts with "secure" TLSA records when the
/*	nexthop destination security level is \fBdane\fR, but the MX
/*	record was found via an "insecure" MX lookup.
/* .PP
/*	Available in Postfix version 3.2 and later:
/* .IP "\fBtls_eecdh_auto_curves (see 'postconf -d' output)\fR"
/*	The prioritized list of elliptic curves supported by the Postfix
/*	SMTP client and server.
/* .PP
/*	Available in Postfix version 3.4 and later:
/* .IP "\fBsmtp_tls_connection_reuse (no)\fR"
/*	Try to make multiple deliveries per TLS-encrypted connection.
/* .IP "\fBsmtp_tls_chain_files (empty)\fR"
/*	List of one or more PEM files, each holding one or more private keys
/*	directly followed by a corresponding certificate chain.
/* .IP "\fBsmtp_tls_servername (empty)\fR"
/*	Optional name to send to the remote SMTP server in the TLS Server
/*	Name Indication (SNI) extension.
/* .PP
/*	Available in Postfix 3.5, 3.4.6, 3.3.5, 3.2.10, 3.1.13 and later:
/* .IP "\fBtls_fast_shutdown_enable (yes)\fR"
/*	A workaround for implementations that hang Postfix while shutting
/*	down a TLS session, until Postfix times out.
/* .PP
/*	Available in Postfix version 3.8 and later:
/* .IP "\fBtls_ffdhe_auto_groups (see 'postconf -d' output)\fR"
/*	The prioritized list of finite-field Diffie-Hellman ephemeral
/*	(FFDHE) key exchange groups supported by the Postfix SMTP client and
/*	server.
/* .PP
/*	Available in Postfix 3.9, 3.8.1, 3.7.6, 3.6.10, 3.5.20 and later:
/* .IP "\fBtls_config_file (default)\fR"
/*	Optional configuration file with baseline OpenSSL settings.
/* .IP "\fBtls_config_name (empty)\fR"
/*	The application name passed by Postfix to OpenSSL library
/*	initialization functions.
/* .PP
/*	Available in Postfix version 3.9 and later:
/* .IP "\fBsmtp_tls_enable_rpk (no)\fR"
/*	Request that remote SMTP servers send an RFC7250 raw public key
/*	instead of an X.509 certificate.
/* OBSOLETE STARTTLS CONTROLS
/* .ad
/* .fi
/*	The following configuration parameters exist for compatibility
/*	with Postfix versions before 2.3. Support for these will
/*	be removed in a future release.
/* .IP "\fBsmtp_use_tls (no)\fR"
/*	Opportunistic mode: use TLS when a remote SMTP server announces
/*	STARTTLS support, otherwise send the mail in the clear.
/* .IP "\fBsmtp_enforce_tls (no)\fR"
/*	Enforcement mode: require that remote SMTP servers use TLS
/*	encryption, and never send mail in the clear.
/* .IP "\fBsmtp_tls_enforce_peername (yes)\fR"
/*	With mandatory TLS encryption, require that the remote SMTP
/*	server hostname matches the information in the remote SMTP server
/*	certificate.
/* .IP "\fBsmtp_tls_per_site (empty)\fR"
/*	Optional lookup tables with the Postfix SMTP client TLS usage
/*	policy by next-hop destination and by remote SMTP server hostname.
/* .IP "\fBsmtp_tls_cipherlist (empty)\fR"
/*	Obsolete Postfix < 2.3 control for the Postfix SMTP client TLS
/*	cipher list.
/* RESOURCE AND RATE CONTROLS
/* .ad
/* .fi
/* .IP "\fBsmtp_connect_timeout (30s)\fR"
/*	The Postfix SMTP client time limit for completing a TCP connection, or
/*	zero (use the operating system built-in time limit).
/* .IP "\fBsmtp_helo_timeout (300s)\fR"
/*	The Postfix SMTP client time limit for sending the HELO or EHLO command,
/*	and for receiving the initial remote SMTP server response.
/* .IP "\fBlmtp_lhlo_timeout (300s)\fR"
/*	The Postfix LMTP client time limit for sending the LHLO command,
/*	and for receiving the initial remote LMTP server response.
/* .IP "\fBsmtp_xforward_timeout (300s)\fR"
/*	The Postfix SMTP client time limit for sending the XFORWARD command,
/*	and for receiving the remote SMTP server response.
/* .IP "\fBsmtp_mail_timeout (300s)\fR"
/*	The Postfix SMTP client time limit for sending the MAIL FROM command,
/*	and for receiving the remote SMTP server response.
/* .IP "\fBsmtp_rcpt_timeout (300s)\fR"
/*	The Postfix SMTP client time limit for sending the SMTP RCPT TO
/*	command, and for receiving the remote SMTP server response.
/* .IP "\fBsmtp_data_init_timeout (120s)\fR"
/*	The Postfix SMTP client time limit for sending the SMTP DATA command,
/*	and for receiving the remote SMTP server response.
/* .IP "\fBsmtp_data_xfer_timeout (180s)\fR"
/*	The Postfix SMTP client time limit for sending the SMTP message content.
/* .IP "\fBsmtp_data_done_timeout (600s)\fR"
/*	The Postfix SMTP client time limit for sending the SMTP ".", and
/*	for receiving the remote SMTP server response.
/* .IP "\fBsmtp_quit_timeout (300s)\fR"
/*	The Postfix SMTP client time limit for sending the QUIT command,
/*	and for receiving the remote SMTP server response.
/* .PP
/*	Available in Postfix version 2.1 and later:
/* .IP "\fBsmtp_mx_address_limit (5)\fR"
/*	The maximal number of MX (mail exchanger) IP addresses that can
/*	result from Postfix SMTP client mail exchanger lookups, or zero (no
/*	limit).
/* .IP "\fBsmtp_mx_session_limit (2)\fR"
/*	The maximal number of SMTP sessions per delivery request before
/*	the Postfix SMTP client
/*	gives up or delivers to a fall-back relay host, or zero (no
/*	limit).
/* .IP "\fBsmtp_rset_timeout (20s)\fR"
/*	The Postfix SMTP client time limit for sending the RSET command,
/*	and for receiving the remote SMTP server response.
/* .PP
/*	Available in Postfix version 2.2 and earlier:
/* .IP "\fBlmtp_cache_connection (yes)\fR"
/*	Keep Postfix LMTP client connections open for up to $max_idle
/*	seconds.
/* .PP
/*	Available in Postfix version 2.2 and later:
/* .IP "\fBsmtp_connection_cache_destinations (empty)\fR"
/*	Permanently enable SMTP connection caching for the specified
/*	destinations.
/* .IP "\fBsmtp_connection_cache_on_demand (yes)\fR"
/*	Temporarily enable SMTP connection caching while a destination
/*	has a high volume of mail in the active queue.
/* .IP "\fBsmtp_connection_reuse_time_limit (300s)\fR"
/*	The amount of time during which Postfix will use an SMTP
/*	connection repeatedly.
/* .IP "\fBsmtp_connection_cache_time_limit (2s)\fR"
/*	When SMTP connection caching is enabled, the amount of time that
/*	an unused SMTP client socket is kept open before it is closed.
/* .PP
/*	Available in Postfix version 2.3 and later:
/* .IP "\fBconnection_cache_protocol_timeout (5s)\fR"
/*	Time limit for connection cache connect, send or receive
/*	operations.
/* .PP
/*	Available in Postfix version 2.9 - 3.6:
/* .IP "\fBsmtp_per_record_deadline (no)\fR"
/*	Change the behavior of the smtp_*_timeout time limits, from a
/*	time limit per read or write system call, to a time limit to send
/*	or receive a complete record (an SMTP command line, SMTP response
/*	line, SMTP message content line, or TLS protocol message).
/* .PP
/*	Available in Postfix version 2.11 and later:
/* .IP "\fBsmtp_connection_reuse_count_limit (0)\fR"
/*	When SMTP connection caching is enabled, the number of times
/*	that an SMTP session may be reused before it is closed, or zero (no
/*	limit).
/* .PP
/*	Available in Postfix version 3.4 and later:
/* .IP "\fBsmtp_tls_connection_reuse (no)\fR"
/*	Try to make multiple deliveries per TLS-encrypted connection.
/* .PP
/*	Available in Postfix version 3.7 and later:
/* .IP "\fBsmtp_per_request_deadline (no)\fR"
/*	Change the behavior of the smtp_*_timeout time limits, from a
/*	time limit per plaintext or TLS read or write call, to a combined
/*	time limit for sending a complete SMTP request and for receiving a
/*	complete SMTP response.
/* .IP "\fBsmtp_min_data_rate (500)\fR"
/*	The minimum plaintext data transfer rate in bytes/second for
/*	DATA requests, when deadlines are enabled with smtp_per_request_deadline.
/* .PP
/*	Implemented in the qmgr(8) daemon:
/* .IP "\fBtransport_destination_concurrency_limit ($default_destination_concurrency_limit)\fR"
/*	A transport-specific override for the
/*	default_destination_concurrency_limit parameter value, where
/*	\fItransport\fR is the master.cf name of the message delivery
/*	transport.
/* .IP "\fBtransport_destination_recipient_limit ($default_destination_recipient_limit)\fR"
/*	A transport-specific override for the
/*	default_destination_recipient_limit parameter value, where
/*	\fItransport\fR is the master.cf name of the message delivery
/*	transport.
/* SMTPUTF8 CONTROLS
/* .ad
/* .fi
/*	Preliminary SMTPUTF8 support is introduced with Postfix 3.0.
/* .IP "\fBsmtputf8_enable (yes)\fR"
/*	Enable preliminary SMTPUTF8 support for the protocols described
/*	in RFC 6531, RFC 6532, and RFC 6533.
/* .IP "\fBsmtputf8_autodetect_classes (sendmail, verify)\fR"
/*	Detect that a message requires SMTPUTF8 support for the specified
/*	mail origin classes.
/* .PP
/*	Available in Postfix version 3.2 and later:
/* .IP "\fBenable_idna2003_compatibility (no)\fR"
/*	Enable 'transitional' compatibility between IDNA2003 and IDNA2008,
/*	when converting UTF-8 domain names to/from the ASCII form that is
/*	used for DNS lookups.
/* TROUBLE SHOOTING CONTROLS
/* .ad
/* .fi
/* .IP "\fBdebug_peer_level (2)\fR"
/*	The increment in verbose logging level when a nexthop destination,
/*	remote client or server name or network address matches a pattern
/*	given with the debug_peer_list parameter.
/* .IP "\fBdebug_peer_list (empty)\fR"
/*	Optional list of nexthop destination, remote client or server
/*	name or network address patterns that, if matched, cause the verbose
/*	logging level to increase by the amount specified in $debug_peer_level.
/* .IP "\fBerror_notice_recipient (postmaster)\fR"
/*	The recipient of postmaster notifications about mail delivery
/*	problems that are caused by policy, resource, software or protocol
/*	errors.
/* .IP "\fBinternal_mail_filter_classes (empty)\fR"
/*	What categories of Postfix-generated mail are subject to
/*	before-queue content inspection by non_smtpd_milters, header_checks
/*	and body_checks.
/* .IP "\fBnotify_classes (resource, software)\fR"
/*	The list of error classes that are reported to the postmaster.
/* MISCELLANEOUS CONTROLS
/* .ad
/* .fi
/* .IP "\fBbest_mx_transport (empty)\fR"
/*	Where the Postfix SMTP client should deliver mail when it detects
/*	a "mail loops back to myself" error condition.
/* .IP "\fBconfig_directory (see 'postconf -d' output)\fR"
/*	The default location of the Postfix main.cf and master.cf
/*	configuration files.
/* .IP "\fBdaemon_timeout (18000s)\fR"
/*	How much time a Postfix daemon process may take to handle a
/*	request before it is terminated by a built-in watchdog timer.
/* .IP "\fBdelay_logging_resolution_limit (2)\fR"
/*	The maximal number of digits after the decimal point when logging
/*	sub-second delay values.
/* .IP "\fBdisable_dns_lookups (no)\fR"
/*	Disable DNS lookups in the Postfix SMTP and LMTP clients.
/* .IP "\fBinet_interfaces (all)\fR"
/*	The local network interface addresses that this mail system
/*	receives mail on.
/* .IP "\fBinet_protocols (see 'postconf -d' output)\fR"
/*	The Internet protocols Postfix will attempt to use when making
/*	or accepting connections.
/* .IP "\fBipc_timeout (3600s)\fR"
/*	The time limit for sending or receiving information over an internal
/*	communication channel.
/* .IP "\fBlmtp_assume_final (no)\fR"
/*	When a remote LMTP server announces no DSN support, assume that
/*	the
/*	server performs final delivery, and send "delivered" delivery status
/*	notifications instead of "relayed".
/* .IP "\fBlmtp_tcp_port (24)\fR"
/*	The default TCP port that the Postfix LMTP client connects to.
/* .IP "\fBmax_idle (100s)\fR"
/*	The maximum amount of time that an idle Postfix daemon process waits
/*	for an incoming connection before terminating voluntarily.
/* .IP "\fBmax_use (100)\fR"
/*	The maximal number of incoming connections that a Postfix daemon
/*	process will service before terminating voluntarily.
/* .IP "\fBprocess_id (read-only)\fR"
/*	The process ID of a Postfix command or daemon process.
/* .IP "\fBprocess_name (read-only)\fR"
/*	The process name of a Postfix command or daemon process.
/* .IP "\fBproxy_interfaces (empty)\fR"
/*	The remote network interface addresses that this mail system receives mail
/*	on by way of a proxy or network address translation unit.
/* .IP "\fBsmtp_address_preference (any)\fR"
/*	The address type ("ipv6", "ipv4" or "any") that the Postfix
/*	SMTP client will try first, when a destination has IPv6 and IPv4
/*	addresses with equal MX preference.
/* .IP "\fBsmtp_bind_address (empty)\fR"
/*	An optional numerical network address that the Postfix SMTP client
/*	should bind to when making an IPv4 connection.
/* .IP "\fBsmtp_bind_address6 (empty)\fR"
/*	An optional numerical network address that the Postfix SMTP client
/*	should bind to when making an IPv6 connection.
/* .IP "\fBsmtp_helo_name ($myhostname)\fR"
/*	The hostname to send in the SMTP HELO or EHLO command.
/* .IP "\fBlmtp_lhlo_name ($myhostname)\fR"
/*	The hostname to send in the LMTP LHLO command.
/* .IP "\fBsmtp_host_lookup (dns)\fR"
/*	What mechanisms the Postfix SMTP client uses to look up a host's
/*	IP address.
/* .IP "\fBsmtp_randomize_addresses (yes)\fR"
/*	Randomize the order of equal-preference MX host addresses.
/* .IP "\fBsyslog_facility (mail)\fR"
/*	The syslog facility of Postfix logging.
/* .IP "\fBsyslog_name (see 'postconf -d' output)\fR"
/*	A prefix that is prepended to the process name in syslog
/*	records, so that, for example, "smtpd" becomes "prefix/smtpd".
/* .PP
/*	Available with Postfix 2.2 and earlier:
/* .IP "\fBfallback_relay (empty)\fR"
/*	Optional list of relay hosts for SMTP destinations that can't be
/*	found or that are unreachable.
/* .PP
/*	Available with Postfix 2.3 and later:
/* .IP "\fBsmtp_fallback_relay ($fallback_relay)\fR"
/*	Optional list of relay destinations that will be used when an
/*	SMTP destination is not found, or when delivery fails due to a
/*	non-permanent error.
/* .PP
/*	Available with Postfix 3.0 and later:
/* .IP "\fBsmtp_address_verify_target (rcpt)\fR"
/*	In the context of email address verification, the SMTP protocol
/*	stage that determines whether an email address is deliverable.
/* .PP
/*	Available with Postfix 3.1 and later:
/* .IP "\fBlmtp_fallback_relay (empty)\fR"
/*	Optional list of relay hosts for LMTP destinations that can't be
/*	found or that are unreachable.
/* .PP
/*	Available with Postfix 3.2 and later:
/* .IP "\fBsmtp_tcp_port (smtp)\fR"
/*	The default TCP port that the Postfix SMTP client connects to.
/* .PP
/*	Available in Postfix 3.3 and later:
/* .IP "\fBservice_name (read-only)\fR"
/*	The master.cf service name of a Postfix daemon process.
/* .PP
/*	Available in Postfix 3.7 and later:
/* .IP "\fBsmtp_bind_address_enforce (no)\fR"
/*	Defer delivery when the Postfix SMTP client cannot apply the
/*	smtp_bind_address or smtp_bind_address6 setting.
/* SEE ALSO
/*	generic(5), output address rewriting
/*	header_checks(5), message header content inspection
/*	body_checks(5), body parts content inspection
/*	qmgr(8), queue manager
/*	bounce(8), delivery status reports
/*	scache(8), connection cache server
/*	postconf(5), configuration parameters
/*	master(5), generic daemon options
/*	master(8), process manager
/*	tlsmgr(8), TLS session and PRNG management
/*	postlogd(8), Postfix logging
/*	syslogd(8), system logging
/* README FILES
/* .ad
/* .fi
/*	Use "\fBpostconf readme_directory\fR" or
/*	"\fBpostconf html_directory\fR" to locate this information.
/* .na
/* .nf
/*	SASL_README, Postfix SASL howto
/*	TLS_README, Postfix STARTTLS howto
/* LICENSE
/* .ad
/* .fi
/*	The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/*	Wietse Venema
/*	IBM T.J. Watson Research
/*	P.O. Box 704
/*	Yorktown Heights, NY 10598, USA
/*
/*	Wietse Venema
/*	Google, Inc.
/*	111 8th Avenue
/*	New York, NY 10011, USA
/*
/*	Command pipelining in cooperation with:
/*	Jon Ribbens
/*	Oaktree Internet Solutions Ltd.,
/*	Internet House,
/*	Canal Basin,
/*	Coventry,
/*	CV1 4LY, United Kingdom.
/*
/*	SASL support originally by:
/*	Till Franke
/*	SuSE Rhein/Main AG
/*	65760 Eschborn, Germany
/*
/*	TLS support originally by:
/*	Lutz Jaenicke
/*	BTU Cottbus
/*	Allgemeine Elektrotechnik
/*	Universitaetsplatz 3-4
/*	D-03044 Cottbus, Germany
/*
/*	Revised TLS and SMTP connection cache support by:
/*	Victor Duchovni
/*	Morgan Stanley
/*--*/

/* System library. */

#include <sys_defs.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <dict.h>
#include <stringops.h>

/* Utility library. */

#include <msg.h>
#include <mymalloc.h>
#include <name_mask.h>
#include <name_code.h>
#include <byte_mask.h>

/* Global library. */

#include <deliver_request.h>
#include <delivered_hdr.h>
#include <mail_proto.h>
#include <mail_params.h>
#include <mail_version.h>
#include <mail_conf.h>
#include <debug_peer.h>
#include <flush_clnt.h>
#include <scache.h>
#include <string_list.h>
#include <maps.h>
#include <ext_prop.h>
#include <hfrom_format.h>

/* DNS library. */

#include <dns.h>

/* Single server skeleton. */

#include <mail_server.h>

/* Application-specific. */

#include "smtp.h"
#include "smtp_sasl.h"

 /*
  * Tunable parameters. These have compiled-in defaults that can be overruled
  * by settings in the global Postfix configuration file.
  */
int     var_smtp_conn_tmout;
int     var_smtp_helo_tmout;
int     var_smtp_xfwd_tmout;
int     var_smtp_mail_tmout;
int     var_smtp_rcpt_tmout;
int     var_smtp_data0_tmout;
int     var_smtp_data1_tmout;
int     var_smtp_data2_tmout;
int     var_smtp_rset_tmout;
int     var_smtp_quit_tmout;
char   *var_notify_classes;
int     var_smtp_skip_5xx_greeting;
int     var_ign_mx_lookup_err;
int     var_skip_quit_resp;
char   *var_fallback_relay;
char   *var_bestmx_transp;
char   *var_error_rcpt;
int     var_smtp_always_ehlo;
int     var_smtp_never_ehlo;
char   *var_smtp_sasl_opts;
char   *var_smtp_sasl_path;
char   *var_smtp_sasl_passwd;
char   *var_smtp_sasl_passwd_res_delim;
bool    var_smtp_sasl_enable;
char   *var_smtp_sasl_mechs;
char   *var_smtp_sasl_type;
char   *var_smtp_bind_addr;
char   *var_smtp_bind_addr6;
char   *var_smtp_vrfy_tgt;
bool    var_smtp_rand_addr;
int     var_smtp_pix_thresh;
int     var_queue_run_delay;
int     var_min_backoff_time;
int     var_smtp_pix_delay;
int     var_smtp_line_limit;
char   *var_smtp_helo_name;
char   *var_smtp_host_lookup;
bool    var_smtp_quote_821_env;
bool    var_smtp_defer_mxaddr;
bool    var_smtp_send_xforward;
int     var_smtp_mxaddr_limit;
int     var_smtp_mxsess_limit;
int     var_smtp_cache_conn;
int     var_smtp_reuse_time;
int     var_smtp_reuse_count;
char   *var_smtp_cache_dest;
char   *var_scache_service;		/* You can now leave this here. */
bool    var_smtp_cache_demand;
char   *var_smtp_ehlo_dis_words;
char   *var_smtp_ehlo_dis_maps;
char   *var_smtp_addr_pref;

char   *var_smtp_tls_level;
bool    var_smtp_use_tls;
bool    var_smtp_enforce_tls;
char   *var_smtp_tls_per_site;
char   *var_smtp_tls_policy;
bool    var_smtp_tls_wrappermode;
bool    var_smtp_tls_conn_reuse;
char   *var_tlsproxy_service;

#ifdef USE_TLS
char   *var_smtp_sasl_tls_opts;
char   *var_smtp_sasl_tlsv_opts;
int     var_smtp_starttls_tmout;
char   *var_smtp_tls_CAfile;
char   *var_smtp_tls_CApath;
char   *var_smtp_tls_chain_files;
char   *var_smtp_tls_cert_file;
char   *var_smtp_tls_mand_ciph;
char   *var_smtp_tls_excl_ciph;
char   *var_smtp_tls_mand_excl;
char   *var_smtp_tls_dcert_file;
char   *var_smtp_tls_dkey_file;
bool    var_smtp_tls_enforce_peername;
char   *var_smtp_tls_key_file;
char   *var_smtp_tls_loglevel;
bool    var_smtp_tls_note_starttls_offer;
char   *var_smtp_tls_mand_proto;
char   *var_smtp_tls_sec_cmatch;
int     var_smtp_tls_scert_vd;
char   *var_smtp_tls_vfy_cmatch;
char   *var_smtp_tls_fpt_cmatch;
char   *var_smtp_tls_fpt_dgst;
char   *var_smtp_tls_tafile;
char   *var_smtp_tls_proto;
char   *var_smtp_tls_ciph;
char   *var_smtp_tls_eccert_file;
char   *var_smtp_tls_eckey_file;
char   *var_smtp_tls_sni;
bool    var_smtp_tls_blk_early_mail_reply;
bool    var_smtp_tls_force_tlsa;
char   *var_smtp_tls_insecure_mx_policy;
bool    var_smtp_tls_enable_rpk;

#endif

char   *var_smtp_generic_maps;
char   *var_prop_extension;
bool    var_smtp_sender_auth;
char   *var_smtp_tcp_port;
int     var_scache_proto_tmout;
bool    var_smtp_cname_overr;
char   *var_smtp_pix_bug_words;
char   *var_smtp_pix_bug_maps;
char   *var_cyrus_conf_path;
char   *var_smtp_head_chks;
char   *var_smtp_mime_chks;
char   *var_smtp_nest_chks;
char   *var_smtp_body_chks;
char   *var_smtp_resp_filter;
bool    var_lmtp_assume_final;
char   *var_smtp_dns_res_opt;
char   *var_smtp_dns_support;
bool    var_smtp_dummy_mail_auth;
char   *var_smtp_dsn_filter;
char   *var_smtp_dns_re_filter;
bool    var_smtp_balance_inet_proto;
bool    var_smtp_req_deadline;
int     var_smtp_min_data_rate;
char   *var_use_srv_lookup;
bool    var_ign_srv_lookup_err;
bool    var_allow_srv_fallback;

 /* Special handling of 535 AUTH errors. */
char   *var_smtp_sasl_auth_cache_name;
int     var_smtp_sasl_auth_cache_time;
bool    var_smtp_sasl_auth_soft_bounce;

char   *var_hfrom_format;
bool    var_smtp_bind_addr_enforce;

 /*
  * Global variables.
  */
int     smtp_mode;
int     smtp_host_lookup_mask;
int     smtp_dns_support;
STRING_LIST *smtp_cache_dest;
SCACHE *smtp_scache;
MAPS   *smtp_ehlo_dis_maps;
MAPS   *smtp_generic_maps;
int     smtp_ext_prop_mask;
unsigned smtp_dns_res_opt;
MAPS   *smtp_pix_bug_maps;
HBC_CHECKS *smtp_header_checks;		/* limited header checks */
HBC_CHECKS *smtp_body_checks;		/* limited body checks */
SMTP_CLI_ATTR smtp_cli_attr;		/* parsed command-line */
int     smtp_hfrom_format;		/* postmaster notifications */
STRING_LIST *smtp_use_srv_lookup;

#ifdef USE_TLS

 /*
  * OpenSSL client state (opaque handle)
  */
TLS_APPL_STATE *smtp_tls_ctx;
int     smtp_tls_insecure_mx_policy;

#endif

 /*
  * IPv6 preference.
  */
static int smtp_addr_pref;

/* get_cli_attr - get command-line attributes */

static void get_cli_attr(SMTP_CLI_ATTR *attr, char **argv)
{
    const char myname[] = "get_cli_attr";
    const char *last_flags = "flags=";	/* i.e. empty */
    static const BYTE_MASK flags_map[] = {
	'D', SMTP_CLI_FLAG_DELIVERED_TO,
	'O', SMTP_CLI_FLAG_ORIG_RCPT,
	'R', SMTP_CLI_FLAG_RETURN_PATH,
	'X', SMTP_CLI_FLAG_FINAL_DELIVERY,
	0,
    };

    /*
     * Initialize.
     */
    attr->flags = 0;

    /*
     * Iterate over the command-line attribute list. Errors are fatal.
     */
    for ( /* void */ ; *argv != 0; argv++) {

	/*
	 * flags=stuff. Errors are fatal.
	 */
	if (strncasecmp("flags=", *argv, sizeof("flags=") - 1) == 0) {
	    last_flags = *argv;
	    if (msg_verbose)
		msg_info("%s: %s", myname, last_flags);
	    attr->flags = byte_mask(*argv, flags_map,
				    *argv + sizeof("flags=") - 1);
	}

	/*
	 * Bad.
	 */
	else
	    msg_fatal("unknown attribute name: %s", *argv);
    }

    /*
     * Backwards compatibility, redundancy, and obsolescence.
     */
    if (!smtp_mode && var_lmtp_assume_final
	&& (attr->flags & SMTP_CLI_FLAG_FINAL_DELIVERY) == 0) {
	attr->flags |= SMTP_CLI_FLAG_FINAL_DELIVERY;
	msg_warn("%s is obsolete; instead, specify \"%sX\" in %s",
		 VAR_LMTP_ASSUME_FINAL, last_flags, MASTER_CONF_FILE);
    }
}

/* deliver_message - deliver message with extreme prejudice */

static int deliver_message(const char *service, DELIVER_REQUEST *request)
{
    SMTP_STATE *state;
    int     result;

    if (msg_verbose)
	msg_info("deliver_message: from %s", request->sender);

    /*
     * Sanity checks. The smtp server is unprivileged and chrooted, so we can
     * afford to distribute the data censoring code, instead of having it all
     * in one place.
     */
    if (request->nexthop[0] == 0)
	msg_fatal("empty nexthop hostname");
    if (request->rcpt_list.len <= 0)
	msg_fatal("recipient count: %d", request->rcpt_list.len);

    /*
     * D flag checks.
     */
    if (smtp_cli_attr.flags & SMTP_CLI_FLAG_DELIVERED_TO) {

	/*
	 * The D flag cannot be specified for multi-recipient deliveries.
	 */
	if (request->rcpt_list.len > 1) {
	    msg_warn("flag `D' requires %s_destination_recipient_limit = 1",
		     service);
	    return (reject_deliver_request(service, request, "4.3.5",
					"mail system configuration error"));
	}

	/*
	 * The recipient cannot appear in a Delivered-To: header.
	 */
	else {
	    DELIVERED_HDR_INFO *delivered_info = delivered_hdr_init(
			  request->fp, request->data_offset, FOLD_ADDR_ALL);
	    VSTRING *generic_rcpt = vstring_alloc(100);
	    int     have_delivered_loop;

	    smtp_rewrite_generic_internal(generic_rcpt,
					  request->rcpt_list.info->address);
	    have_delivered_loop = delivered_hdr_find(
					 delivered_info, STR(generic_rcpt));
	    vstring_free(generic_rcpt);
	    delivered_hdr_free(delivered_info);
	    if (have_delivered_loop) {
		return (reject_deliver_request(service, request, "5.4.6",
					       "mail forwarding loop for %s",
					 request->rcpt_list.info->address));
	    }
	}
    }

    /*
     * The O flag cannot be specified for multi-recipient deliveries.
     */
    if ((smtp_cli_attr.flags & SMTP_CLI_FLAG_ORIG_RCPT)
	&& request->rcpt_list.len > 1) {
	msg_warn("flag `O' requires %s_destination_recipient_limit = 1",
		 service);
	return (reject_deliver_request(service, request, "4.3.5",
				       "mail system configuration error"));
    }

    /*
     * Initialize. Bundle all information about the delivery request, so that
     * we can produce understandable diagnostics when something goes wrong
     * many levels below. The alternative would be to make everything global.
     */
    state = smtp_state_alloc();
    state->request = request;
    state->src = request->fp;
    state->service = service;
    state->misc_flags |= smtp_addr_pref;
    state->debug_peer_per_nexthop =
	debug_peer_check(request->nexthop, "noaddr");
    SMTP_RCPT_INIT(state);

    /*
     * Establish an SMTP session and deliver this message to all requested
     * recipients. At the end, notify the postmaster of any protocol errors.
     * Optionally deliver mail locally when this machine is the best mail
     * exchanger.
     */
    result = smtp_connect(state);

    /*
     * Clean up.
     */
    smtp_state_free(state);

    return (result);
}

/* smtp_service - perform service for client */

static void smtp_service(VSTREAM *client_stream, char *service,
			         char **unused_argv)
{
    DELIVER_REQUEST *request;
    int     status;

    /*
     * This routine runs whenever a client connects to the UNIX-domain socket
     * dedicated to remote SMTP delivery service. What we see below is a
     * little protocol to (1) tell the queue manager that we are ready, (2)
     * read a request from the queue manager, and (3) report the completion
     * status of that request. All connection-management stuff is handled by
     * the common code in single_server.c.
     */
    if ((request = deliver_request_read(client_stream)) != 0) {
	status = deliver_message(service, request);
	deliver_request_done(client_stream, request, status);
    }
}

/* post_init - post-jail initialization */

static void post_init(char *unused_name, char **argv)
{
    static const NAME_MASK lookup_masks[] = {
	SMTP_HOST_LOOKUP_DNS, SMTP_HOST_FLAG_DNS,
	SMTP_HOST_LOOKUP_NATIVE, SMTP_HOST_FLAG_NATIVE,
	0,
    };
    static const NAME_MASK dns_res_opt_masks[] = {
	SMTP_DNS_RES_OPT_DEFNAMES, RES_DEFNAMES,
	SMTP_DNS_RES_OPT_DNSRCH, RES_DNSRCH,
	0,
    };
    static const NAME_CODE dns_support[] = {
	SMTP_DNS_SUPPORT_DISABLED, SMTP_DNS_DISABLED,
	SMTP_DNS_SUPPORT_ENABLED, SMTP_DNS_ENABLED,
#if (RES_USE_DNSSEC != 0) && (RES_USE_EDNS0 != 0)
	SMTP_DNS_SUPPORT_DNSSEC, SMTP_DNS_DNSSEC,
#endif
	0, SMTP_DNS_INVALID,
    };

    if (*var_smtp_dns_support == 0) {
	/* Backwards compatible empty setting */
	smtp_dns_support =
	    var_disable_dns ? SMTP_DNS_DISABLED : SMTP_DNS_ENABLED;
    } else {
	smtp_dns_support =
	    name_code(dns_support, NAME_CODE_FLAG_NONE, var_smtp_dns_support);
	if (smtp_dns_support == SMTP_DNS_INVALID)
	    msg_fatal("invalid %s: \"%s\"", VAR_LMTP_SMTP(DNS_SUPPORT),
		      var_smtp_dns_support);
	var_disable_dns = (smtp_dns_support == SMTP_DNS_DISABLED);
    }

#ifdef USE_TLS
    if (smtp_mode) {
	smtp_tls_insecure_mx_policy =
	    tls_level_lookup(var_smtp_tls_insecure_mx_policy);
	switch (smtp_tls_insecure_mx_policy) {
	case TLS_LEV_MAY:
	case TLS_LEV_ENCRYPT:
	case TLS_LEV_DANE:
	    break;
	default:
	    msg_fatal("invalid %s: \"%s\"", VAR_SMTP_TLS_INSECURE_MX_POLICY,
		      var_smtp_tls_insecure_mx_policy);
	}
    }
#endif

    /*
     * Select hostname lookup mechanisms.
     */
    if (smtp_dns_support == SMTP_DNS_DISABLED)
	smtp_host_lookup_mask = SMTP_HOST_FLAG_NATIVE;
    else
	smtp_host_lookup_mask =
	    name_mask(VAR_LMTP_SMTP(HOST_LOOKUP), lookup_masks,
		      var_smtp_host_lookup);
    if (msg_verbose)
	msg_info("host name lookup methods: %s",
		 str_name_mask(VAR_LMTP_SMTP(HOST_LOOKUP), lookup_masks,
			       smtp_host_lookup_mask));

    /*
     * Session cache instance.
     */
    if (*var_smtp_cache_dest || var_smtp_cache_demand)
#if 0
	smtp_scache = scache_multi_create();
#else
	smtp_scache = scache_clnt_create(var_scache_service,
					 var_scache_proto_tmout,
					 var_ipc_idle_limit,
					 var_ipc_ttl_limit);
#endif

    /*
     * Select DNS query flags.
     */
    smtp_dns_res_opt = name_mask(VAR_LMTP_SMTP(DNS_RES_OPT), dns_res_opt_masks,
				 var_smtp_dns_res_opt);

    /*
     * Address verification.
     */
    smtp_vrfy_init();

    /*
     * Look up service command-line attributes; these do not change during
     * the process lifetime.
     */
    get_cli_attr(&smtp_cli_attr, argv);

    /*
     * header_from format, for postmaster notifications.
     */
    smtp_hfrom_format = hfrom_format_parse(VAR_HFROM_FORMAT, var_hfrom_format);

    /*
     * Service discovery with SRV record lookup.
     */
    if (*var_use_srv_lookup)
	smtp_use_srv_lookup = string_list_init(VAR_USE_SRV_LOOKUP,
					       MATCH_FLAG_RETURN,
					       var_use_srv_lookup);
}

/* pre_init - pre-jail initialization */

static void pre_init(char *unused_name, char **unused_argv)
{
    int     use_tls;
    static const NAME_CODE addr_pref_map[] = {
	INET_PROTO_NAME_IPV6, SMTP_MISC_FLAG_PREF_IPV6,
	INET_PROTO_NAME_IPV4, SMTP_MISC_FLAG_PREF_IPV4,
	INET_PROTO_NAME_ANY, 0,
	0, -1,
    };

    /*
     * The process name, "smtp" or "lmtp", determines the configuration
     * parameters to use, protocol, DSN server reply type, SASL service
     * information lookup, and more. We peeked at the name in the main()
     * function before logging was initialized. Here, we detect and report an
     * invalid process name.
     */
    if (strcmp(var_procname, MAIL_PROC_NAME_SMTP) != 0
	&& strcmp(var_procname, MAIL_PROC_NAME_LMTP) != 0)
	msg_fatal("unexpected process name \"%s\" - "
		  "specify \"%s\" or \"%s\"", var_procname,
		  MAIL_PROC_NAME_SMTP, MAIL_PROC_NAME_LMTP);

    /*
     * Turn on per-peer debugging.
     */
    debug_peer_init();

    /*
     * SASL initialization.
     */
    if (var_smtp_sasl_enable)
#ifdef USE_SASL_AUTH
	smtp_sasl_initialize();
#else
	msg_warn("%s is true, but SASL support is not compiled in",
		 VAR_LMTP_SMTP(SASL_ENABLE));
#endif

    if (*var_smtp_tls_level != 0)
	switch (tls_level_lookup(var_smtp_tls_level)) {
	case TLS_LEV_SECURE:
	case TLS_LEV_VERIFY:
	case TLS_LEV_DANE_ONLY:
	case TLS_LEV_FPRINT:
	case TLS_LEV_ENCRYPT:
	    var_smtp_use_tls = var_smtp_enforce_tls = 1;
	    break;
	case TLS_LEV_DANE:
	case TLS_LEV_MAY:
	    var_smtp_use_tls = 1;
	    var_smtp_enforce_tls = 0;
	    break;
	case TLS_LEV_NONE:
	    var_smtp_use_tls = var_smtp_enforce_tls = 0;
	    break;
	default:
	    /* tls_level_lookup() logs no warning. */
	    /* session_tls_init() assumes that var_smtp_tls_level is sane. */
	    msg_fatal("Invalid TLS level \"%s\"", var_smtp_tls_level);
	}
    use_tls = (var_smtp_use_tls || var_smtp_enforce_tls);

    /*
     * Initialize the TLS data before entering the chroot jail
     */
    if (use_tls || var_smtp_tls_per_site[0] || var_smtp_tls_policy[0]) {
#ifdef USE_TLS
	TLS_CLIENT_INIT_PROPS props;

	tls_pre_jail_init(TLS_ROLE_CLIENT);

	/*
	 * We get stronger type safety and a cleaner interface by combining
	 * the various parameters into a single tls_client_props structure.
	 * 
	 * Large parameter lists are error-prone, so we emulate a language
	 * feature that C does not have natively: named parameter lists.
	 * 
	 * With tlsproxy(8) turned on, this is still needed for DANE-related
	 * initializations.
	 */
	smtp_tls_ctx =
	    TLS_CLIENT_INIT(&props,
			    log_param = VAR_LMTP_SMTP(TLS_LOGLEVEL),
			    log_level = var_smtp_tls_loglevel,
			    verifydepth = var_smtp_tls_scert_vd,
			    cache_type = LMTP_SMTP_SUFFIX(TLS_MGR_SCACHE),
			    chain_files = var_smtp_tls_chain_files,
			    cert_file = var_smtp_tls_cert_file,
			    key_file = var_smtp_tls_key_file,
			    dcert_file = var_smtp_tls_dcert_file,
			    dkey_file = var_smtp_tls_dkey_file,
			    eccert_file = var_smtp_tls_eccert_file,
			    eckey_file = var_smtp_tls_eckey_file,
			    CAfile = var_smtp_tls_CAfile,
			    CApath = var_smtp_tls_CApath,
			    mdalg = var_smtp_tls_fpt_dgst);
	smtp_tls_list_init();
	tls_dane_loglevel(VAR_LMTP_SMTP(TLS_LOGLEVEL), var_smtp_tls_loglevel);
#else
	msg_warn("TLS has been selected, but TLS support is not compiled in");
#endif
    }

    /*
     * Flush client.
     */
    flush_init();

    /*
     * Session cache domain list.
     */
    if (*var_smtp_cache_dest)
	smtp_cache_dest = string_list_init(VAR_SMTP_CACHE_DEST,
					   MATCH_FLAG_RETURN,
					   var_smtp_cache_dest);

    /*
     * EHLO keyword filter.
     */
    if (*var_smtp_ehlo_dis_maps)
	smtp_ehlo_dis_maps = maps_create(VAR_LMTP_SMTP(EHLO_DIS_MAPS),
					 var_smtp_ehlo_dis_maps,
					 DICT_FLAG_LOCK);

    /*
     * PIX bug workarounds.
     */
    if (*var_smtp_pix_bug_maps)
	smtp_pix_bug_maps = maps_create(VAR_LMTP_SMTP(PIX_BUG_MAPS),
					var_smtp_pix_bug_maps,
					DICT_FLAG_LOCK);

    /*
     * Generic maps.
     */
    if (*var_prop_extension)
	smtp_ext_prop_mask =
	    ext_prop_mask(VAR_PROP_EXTENSION, var_prop_extension);
    if (*var_smtp_generic_maps)
	smtp_generic_maps =
	    maps_create(VAR_LMTP_SMTP(GENERIC_MAPS), var_smtp_generic_maps,
			DICT_FLAG_LOCK | DICT_FLAG_FOLD_FIX
			| DICT_FLAG_UTF8_REQUEST);

    /*
     * Header/body checks.
     */
    smtp_header_checks = hbc_header_checks_create(
			       VAR_LMTP_SMTP(HEAD_CHKS), var_smtp_head_chks,
			       VAR_LMTP_SMTP(MIME_CHKS), var_smtp_mime_chks,
			       VAR_LMTP_SMTP(NEST_CHKS), var_smtp_nest_chks,
						  smtp_hbc_callbacks);
    smtp_body_checks = hbc_body_checks_create(
			       VAR_LMTP_SMTP(BODY_CHKS), var_smtp_body_chks,
					      smtp_hbc_callbacks);

    /*
     * Server reply filter.
     */
    if (*var_smtp_resp_filter)
	smtp_chat_resp_filter =
	    dict_open(var_smtp_resp_filter, O_RDONLY,
		      DICT_FLAG_LOCK | DICT_FLAG_FOLD_FIX);

    /*
     * Address family preference.
     */
    if (*var_smtp_addr_pref) {
	smtp_addr_pref = name_code(addr_pref_map, NAME_CODE_FLAG_NONE,
				   var_smtp_addr_pref);
	if (smtp_addr_pref < 0)
	    msg_fatal("bad %s value: %s", VAR_LMTP_SMTP(ADDR_PREF),
		      var_smtp_addr_pref);
    }

    /*
     * DNS reply filter.
     */
    if (*var_smtp_dns_re_filter)
	dns_rr_filter_compile(VAR_LMTP_SMTP(DNS_RE_FILTER),
			      var_smtp_dns_re_filter);
}

/* pre_accept - see if tables have changed */

static void pre_accept(char *unused_name, char **unused_argv)
{
    const char *table;

    if ((table = dict_changed_name()) != 0) {
	msg_info("table %s has changed -- restarting", table);
	exit(0);
    }
}

MAIL_VERSION_STAMP_DECLARE;

/* main - pass control to the single-threaded skeleton */

int     main(int argc, char **argv)
{
    char   *sane_procname;

#include "smtp_params.c"
#include "lmtp_params.c"

    /*
     * Fingerprint executables and core dumps.
     */
    MAIL_VERSION_STAMP_ALLOCATE;

    /*
     * XXX The process name, "smtp" or "lmtp", determines what configuration
     * parameter settings to use, and more. However, at this point, logging
     * and var_procname are not initialized. Here, we peek at the process
     * name to determine what configuration parameter settings to use. Later,
     * we detect and report an invalid process name.
     */
    sane_procname = sane_basename((VSTRING *) 0, argv[0]);
    if (strcmp(sane_procname, MAIL_PROC_NAME_SMTP) == 0)
	smtp_mode = 1;

    /*
     * Initialize with the LMTP or SMTP parameter name space.
     */
    single_server_main(argc, argv, smtp_service,
		       CA_MAIL_SERVER_TIME_TABLE(smtp_mode ?
					 smtp_time_table : lmtp_time_table),
		       CA_MAIL_SERVER_INT_TABLE(smtp_mode ?
					   smtp_int_table : lmtp_int_table),
		       CA_MAIL_SERVER_STR_TABLE(smtp_mode ?
					   smtp_str_table : lmtp_str_table),
		       CA_MAIL_SERVER_BOOL_TABLE(smtp_mode ?
					 smtp_bool_table : lmtp_bool_table),
		       CA_MAIL_SERVER_NBOOL_TABLE(smtp_mode ?
				       smtp_nbool_table : lmtp_nbool_table),
		       CA_MAIL_SERVER_PRE_INIT(pre_init),
		       CA_MAIL_SERVER_POST_INIT(post_init),
		       CA_MAIL_SERVER_PRE_ACCEPT(pre_accept),
		       CA_MAIL_SERVER_BOUNCE_INIT(VAR_SMTP_DSN_FILTER,
						  &var_smtp_dsn_filter),
		       0);
}