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
|
<!doctype html public "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<title>Postfix Backwards-Compatibility Safety Net</title>
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
</head>
<body>
<h1><img src="postfix-logo.jpg" width="203" height="98" ALT="">Postfix
Backwards-Compatibility Safety Net</h1>
<hr>
<h2>Purpose of this document </h2>
<p> Postfix 3.0 introduces a safety net that runs Postfix programs
with backwards-compatible default settings after an upgrade. The
safety net will log a warning whenever a "new" default setting could
have an negative effect on your mail flow. </p>
<p>This document provides information on the following topics: </p>
<ul>
<li> <p> <a href="#overview">Detailed descriptions</a> of Postfix
backwards-compatibility warnings.
<li> <p> What backwards-compatible settings you may have to make
permanent in <a href="postconf.5.html">main.cf</a> or <a href="master.5.html">master.cf</a>. </p>
<li> <p> <a href="#turnoff">How to turn off</a> Postfix
backwards-compatibility warnings. </p>
</ul>
<h2> <a name="overview"> Overview </a> </h2>
<p> With backwards compatibility turned on, Postfix logs a message
whenever a backwards-compatible default setting may be required for
continuity of service. Based on this logging the system administrator
can decide if any backwards-compatible settings need to be made
permanent in main.cf or master.cf, before <a href="#turnoff">turning
off the backwards-compatibility safety net</a> as described at the
end of this document. </p>
<p> The following messages may be logged: </p>
<ul>
<li> <p> <a href="#append_dot_mydomain"> Using backwards-compatible
default setting append_dot_mydomain=yes </a> </p>
<li> <p> <a href="#chroot"> Using backwards-compatible default setting
chroot=y</a> </p>
<li><p> <a href="#relay_restrictions"> Using backwards-compatible
default setting smtpd_relay_restrictions = (empty)</a> </p>
<li> <p> <a href="#mynetworks_style"> Using backwards-compatible
default setting mynetworks_style=subnet </a> </p>
<li> <p> <a href="#relay_domains"> Using backwards-compatible default
setting relay_domains=$mydestination </a> </p>
<li> <p> <a href="#smtputf8_enable"> Using backwards-compatible
default setting smtputf8_enable=no</a> </p>
</ul>
<p> If such a message is logged in the context of a legitimate
request, the system administrator should make the backwards-compatible
setting permanent in <a href="postconf.5.html">main.cf</a> or <a href="master.5.html">master.cf</a>, as detailed in the
sections that follow. </p>
<p> When no more backwards-compatible settings need to be made
permanent, the system administrator should <a href="#turnoff">turn
off the backwards-compatibility safety net</a> as described at the
end of this document. </p>
<h2> <a name="append_dot_mydomain"> Using backwards-compatible default
setting append_dot_mydomain=yes</a> </h2>
<p> The <a href="postconf.5.html#append_dot_mydomain">append_dot_mydomain</a> default value has changed from "yes"
to "no". This could result in unexpected non-delivery of email after
Postfix is updated from an older version. The backwards-compatibility
safety net is designed to prevent such surprises. </p>
<p> As long as the <a href="postconf.5.html#append_dot_mydomain">append_dot_mydomain</a> parameter is left at
its implicit default value, and the <a href="postconf.5.html#compatibility_level">compatibility_level</a> setting is
less than 1, Postfix may log one of the following messages:</p>
<ul>
<li> <p> Messages about missing "localhost" in <a href="postconf.5.html#mydestination">mydestination</a> or
other address class: </p>
<blockquote>
<pre>
postfix/trivial-rewrite[14777]: using backwards-compatible
default setting <a href="postconf.5.html#append_dot_mydomain">append_dot_mydomain</a>=yes to rewrite
"localhost" to "localhost.example.com"; please add
"localhost" to <a href="postconf.5.html#mydestination">mydestination</a> or other address class
</pre>
</blockquote>
<p> If Postfix logs the above message, add "localhost" to
<a href="postconf.5.html#mydestination">mydestination</a> (or <a href="postconf.5.html#virtual_alias_domains">virtual_alias_domains</a>, <a href="postconf.5.html#virtual_mailbox_domains">virtual_mailbox_domains</a>,
or <a href="postconf.5.html#relay_domains">relay_domains</a>) and execute the command "<b>postfix reload</b>".
<li> <p> Messages about incomplete domains in email addresses: </p>
<blockquote>
<pre>
postfix/trivial-rewrite[25835]: using backwards-compatible
default setting <a href="postconf.5.html#append_dot_mydomain">append_dot_mydomain</a>=yes to rewrite "foo" to
"foo.example.com"
</pre>
</blockquote>
<p> If Postfix logs the above message for domains different from
"localhost", and the sender cannot be changed to use complete domain
names in email addresses, then the system administrator should make
the backwards-compatible setting "<a href="postconf.5.html#append_dot_mydomain">append_dot_mydomain</a> = yes" permanent
in <a href="postconf.5.html">main.cf</a>: </p>
<blockquote>
<pre>
# <b>postconf <a href="postconf.5.html#append_dot_mydomain">append_dot_mydomain</a>=yes</b>
# <b>postfix reload</b>
</pre>
</blockquote>
</ul>
<h2> <a name="chroot"> Using backwards-compatible default
setting chroot=y</a> </h2>
<p> The <a href="master.5.html">master.cf</a> chroot default value has changed from "y" (yes)
to "n" (no). The new default avoids the need for copies of system
files under the Postfix queue directory. However, sites with strict
security requirements may want to keep the chroot feature enabled
after updating Postfix from an older version. The backwards-compatibility
safety net is designed allow the administrator to choose if they
want to keep the old behavior. </p>
<p> As long as a <a href="master.5.html">master.cf</a> chroot field is left at its
implicit default value, and the <a href="postconf.5.html#compatibility_level">compatibility_level</a> setting
is less than 1, Postfix may log the following message while it
reads the <a href="master.5.html">master.cf</a> file: </p>
<blockquote>
<pre>
postfix/master[27664]: /etc/postfix/<a href="master.5.html">master.cf</a>: line 72: using
backwards-compatible default setting chroot=y
</pre>
</blockquote>
<p> If this service should remain chrooted, then the system
administrator should make the backwards-compatible setting "chroot
= y" permanent in <a href="master.5.html">master.cf</a>. For example, to update the chroot
setting for the "smtp inet" service: </p>
<blockquote>
<pre>
# <b>postconf -F smtp/inet/chroot=y</b>
# <b>postfix reload</b>
</pre>
</blockquote>
<h2> <a name="relay_restrictions"> Using backwards-compatible default
setting smtpd_relay_restrictions = (empty)</a> </h2>
<p> The <a href="postconf.5.html#smtpd_relay_restrictions">smtpd_relay_restrictions</a> feature was introduced with Postfix
version 2.10, as a safety mechanism for configuration errors in
<a href="postconf.5.html#smtpd_recipient_restrictions">smtpd_recipient_restrictions</a> that could make Postfix an open relay.
</p>
<p> The <a href="postconf.5.html#smtpd_relay_restrictions">smtpd_relay_restrictions</a> implicit default setting forbids
mail to remote destinations from clients that don't match
<a href="postconf.5.html#permit_mynetworks">permit_mynetworks</a> or <a href="postconf.5.html#permit_sasl_authenticated">permit_sasl_authenticated</a>. This could result
in unexpected 'Relay access denied' errors after Postfix is updated
from an older Postfix version. The backwards-compatibility safety
net is designed to prevent such surprises. </p>
<p> When the <a href="postconf.5.html#compatibility_level">compatibility_level</a> less than 1, and the
<a href="postconf.5.html#smtpd_relay_restrictions">smtpd_relay_restrictions</a> parameter is left at its implicit default
setting, Postfix may log the following message: </p>
<blockquote>
<pre>
postfix/smtpd[38463]: using backwards-compatible default setting
"<a href="postconf.5.html#smtpd_relay_restrictions">smtpd_relay_restrictions</a> = (empty)" to avoid "Relay access
denied" error for recipient "user@example.com" from client
"host.example.net[10.0.0.2]"
</pre>
</blockquote>
<p> If this request should not be blocked, then the system
administrator should make the backwards-compatible setting
"<a href="postconf.5.html#smtpd_relay_restrictions">smtpd_relay_restrictions</a>=" (i.e. empty) permanent in <a href="postconf.5.html">main.cf</a>:
<blockquote>
<pre>
# <b>postconf <a href="postconf.5.html#smtpd_relay_restrictions">smtpd_relay_restrictions</a>=</b>
# <b>postfix reload</b>
</pre>
</blockquote>
<h2> <a name="mynetworks_style"> Using backwards-compatible default
setting mynetworks_style=subnet</a> </h2>
<p> The <a href="postconf.5.html#mynetworks_style">mynetworks_style</a> default value has changed from "subnet"
to "host". This parameter is used to implement the "<a href="postconf.5.html#permit_mynetworks">permit_mynetworks</a>"
feature. The change could in unexpected 'access denied' errors after
Postfix is updated from an older version. The backwards-compatibility
safety net is designed to prevent such surprises. </p>
<p> As long as the <a href="postconf.5.html#mynetworks">mynetworks</a> and <a href="postconf.5.html#mynetworks_style">mynetworks_style</a> parameters are
left at their implicit default values, and the <a href="postconf.5.html#compatibility_level">compatibility_level</a>
setting is less than 2, the Postfix SMTP server may log one of the
following messages: </p>
<blockquote>
<pre>
postfix/smtpd[17375]: using backwards-compatible default setting
<a href="postconf.5.html#mynetworks_style">mynetworks_style</a>=subnet to permit request from client
"foo.example.com[10.1.1.1]"
</pre>
</blockquote>
<blockquote>
<pre>
postfix/postscreen[24982]: using backwards-compatible default
setting <a href="postconf.5.html#mynetworks_style">mynetworks_style</a>=subnet to permit request from client
"10.1.1.1"
</pre>
</blockquote>
<p> If the client request should not be rejected, then the system
administrator should make the backwards-compatible setting
"<a href="postconf.5.html#mynetworks_style">mynetworks_style</a> = subnet" permanent in <a href="postconf.5.html">main.cf</a>: </p>
<blockquote>
<pre>
# <b>postconf <a href="postconf.5.html#mynetworks_style">mynetworks_style</a>=subnet</b>
# <b>postfix reload</b>
</pre>
</blockquote>
<h2><a name="relay_domains"> Using backwards-compatible default
setting relay_domains=$mydestination </a> </h2>
<p> The <a href="postconf.5.html#relay_domains">relay_domains</a> default value has changed from "$<a href="postconf.5.html#mydestination">mydestination</a>"
to the empty value. This could result in unexpected 'Relay access
denied' errors or ETRN errors after Postfix is updated from an older
version. The backwards-compatibility safety net is designed to
prevent such surprises. </p>
<p> As long as the <a href="postconf.5.html#relay_domains">relay_domains</a> parameter is left at its implicit
default value, and the <a href="postconf.5.html#compatibility_level">compatibility_level</a> setting is less than 2,
Postfix may log one of the following messages. </p>
<ul>
<li> <p> Messages about accepting mail for a remote domain:</p>
<blockquote>
<pre>
postfix/smtpd[19052]: using backwards-compatible default setting
<a href="postconf.5.html#relay_domains">relay_domains</a>=$<a href="postconf.5.html#mydestination">mydestination</a> to accept mail for domain
"foo.example.com"
</pre>
</blockquote>
<blockquote>
<pre>
postfix/smtpd[19052]: using backwards-compatible default setting
<a href="postconf.5.html#relay_domains">relay_domains</a>=$<a href="postconf.5.html#mydestination">mydestination</a> to accept mail for address
"user@foo.example.com"
</pre>
</blockquote>
<li> <p> Messages about providing ETRN service for a remote domain:</p>
<blockquote>
<pre>
postfix/smtpd[19138]: using backwards-compatible default setting
<a href="postconf.5.html#relay_domains">relay_domains</a>=$<a href="postconf.5.html#mydestination">mydestination</a> to flush mail for domain
"bar.example.com"
</pre>
</blockquote>
<blockquote>
<pre>
postfix/smtp[13945]: using backwards-compatible default setting
<a href="postconf.5.html#relay_domains">relay_domains</a>=$<a href="postconf.5.html#mydestination">mydestination</a> to update fast-flush logfile for
domain "bar.example.com"
</pre>
</blockquote>
</ul>
<p> If Postfix should continue to accept mail for that domain or
continue to provide ETRN service for that domain, then the system
administrator should make the backwards-compatible setting
"<a href="postconf.5.html#relay_domains">relay_domains</a> = $<a href="postconf.5.html#mydestination">mydestination</a>" permanent in <a href="postconf.5.html">main.cf</a>: </p>
<blockquote>
<pre>
# <b>postconf '<a href="postconf.5.html#relay_domains">relay_domains</a>=$<a href="postconf.5.html#mydestination">mydestination</a>'</b>
# <b>postfix reload</b>
</pre>
</blockquote>
<p> Note: quotes are required as indicated above. </p>
<p> Instead of $<a href="postconf.5.html#mydestination">mydestination</a>, it may be better to specify an
explicit list of domain names. </p>
<h2> <a name="smtputf8_enable"> Using backwards-compatible default
setting smtputf8_enable=no</a> </h2>
<p> The <a href="postconf.5.html#smtputf8_enable">smtputf8_enable</a> default value has changed from "no" to "yes.
With the new "yes" setting, the Postfix SMTP server rejects non-ASCII
addresses from clients that don't request SMTPUTF8 support, after
Postfix is updated from an older version. The backwards-compatibility
safety net is designed to prevent such surprises. </p>
<p> As long as the <a href="postconf.5.html#smtputf8_enable">smtputf8_enable</a> parameter is left at its implicit
default value, and the <a href="postconf.5.html#compatibility_level">compatibility_level</a> setting is
less than 1, Postfix logs a warning each time an SMTP command uses a
non-ASCII address localpart without requesting SMTPUTF8 support: </p>
<blockquote>
<pre>
postfix/smtpd[27560]: using backwards-compatible default setting
<a href="postconf.5.html#smtputf8_enable">smtputf8_enable</a>=no to accept non-ASCII sender address
"??@example.org" from localhost[127.0.0.1]
</pre>
</blockquote>
<blockquote>
<pre>
postfix/smtpd[27560]: using backwards-compatible default setting
<a href="postconf.5.html#smtputf8_enable">smtputf8_enable</a>=no to accept non-ASCII recipient address
"??@example.com" from localhost[127.0.0.1]
</pre>
</blockquote>
<p> If the address should not be rejected, and the client cannot
be updated to use SMTPUTF8, then the system administrator should
make the backwards-compatible setting "<a href="postconf.5.html#smtputf8_enable">smtputf8_enable</a> = no" permanent
in <a href="postconf.5.html">main.cf</a>:
<blockquote>
<pre>
# <b>postconf <a href="postconf.5.html#smtputf8_enable">smtputf8_enable</a>=no</b>
# <b>postfix reload</b>
</pre>
</blockquote>
<h2> <a name="turnoff">Turning off the backwards-compatibility safety net</a> </h2>
<p> Backwards compatibility is turned off by updating the
<a href="postconf.5.html#compatibility_level">compatibility_level</a> setting in <a href="postconf.5.html">main.cf</a>. </p>
<blockquote>
<pre>
# <b>postconf <a href="postconf.5.html#compatibility_level">compatibility_level</a>=<i>N</i></b>
# <b>postfix reload</b>
</pre>
</blockquote>
<p> For <i>N</i> specify the number that is logged in your <a href="postfix.1.html">postfix(1)</a>
warning message: </p>
<blockquote>
<pre>
warning: To disable backwards compatibility use "postconf <a href="postconf.5.html#compatibility_level">compatibility_level</a>=<i>N</i>" and "postfix reload"
</pre>
</blockquote>
<p> Sites that don't care about backwards compatibility may set
"<a href="postconf.5.html#compatibility_level">compatibility_level</a> = 9999" at their own risk. </p>
</body>
</html>
|
