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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 16:16:13 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 16:16:13 +0000
commite90fcc54809db2591dc083f43ef54c6ec8c60847 (patch)
treef20bc206c3c2d5d59d37c46c5cf5d53a20642556 /README.UPDATING
parentInitial commit. (diff)
downloadexim4-e90fcc54809db2591dc083f43ef54c6ec8c60847.tar.xz
exim4-e90fcc54809db2591dc083f43ef54c6ec8c60847.zip
Adding upstream version 4.96.upstream/4.96upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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+This document contains detailed information about incompatibilities that might
+be encountered when upgrading from one release of Exim to another. The
+information is in reverse order of release numbers. Mostly these are relatively
+small points, and the configuration file is normally upwards compatible, but
+there have been two big upheavals...
+
+
+**************************************************************************
+* There was a big reworking of the way mail routing works for release *
+* 4.00. Previously used "directors" were abolished, and all routing is *
+* now done by routers. Policy controls for incoming mail are now done by *
+* Access Control Lists instead of separate options. All this means that *
+* pre-4.00 configuration files have to be massively converted. If you *
+* are coming from a 3.xx release, please read the document in the file *
+* doc/Exim4.upgrade, and allow some time to complete the upgrade. *
+* *
+* There was a big reworking of the way domain/host/net/address lists are *
+* handled at release 3.00. If you are coming from a pre-3.00 release, it *
+* might be easier to start again from a default configuration. Otherwise *
+* you need to read doc/Exim3.upgrade and do a double conversion of your *
+* configuration file. *
+**************************************************************************
+
+
+The rest of this document contains information about changes in 4.xx releases
+that might affect a running system.
+
+
+Exim version 4.95
+-----------------
+
+Various length limits have been applied to Exim's parsing of its command-line.
+These are all set to be at least as long as any valid input, so we do not believe
+that any real use-cases have been affected by this.
+
+The names of various drivers (authenticators, routers, transports, ...) have
+always been limited to 64 characters, but before this release the names were
+silently truncated, inviting problems. Now the length limit should be enforced.
+If this affects you, then please rename to use shorter names.
+
+The default maximum number of recipients of a single email has changed from
+"unlimited" (ie: as much as CPU and memory will allow, until something breaks
+badly) to 50,000. You can raise or lower this as you see fit, but we strongly
+caution against using zero/unlimited.
+
+
+Exim version 4.94
+-----------------
+
+Some Transports now refuse to use tainted data in constructing their delivery
+location; this WILL BREAK configurations which are not updated accordingly.
+In particular: any Transport use of $local_part which has been relying upon
+check_local_user far away in the Router to make it safe, should be updated to
+replace $local_part with $local_part_data.
+
+Attempting to remove, in router or transport, a header name that ends with
+an asterisk (which is a standards-legal name) will now result in all headers
+named starting with the string before the asterisk being removed. We recommend
+staying away from such names, if they are private ones (and in case of future
+enhancements, alao header names that look like REs).
+
+
+Exim version 4.93
+-----------------
+
+For a detailed list of changes that might affect Exim's operation with
+an unchanged configuration, please see the doc/ChangeLog file.
+
+Build:
+
+ * SUPPORT_DMARC replaces EXPERIMENTAL_DMARC
+
+ * DISABLE_TLS replaces SUPPORT_TLS
+
+ * Bump the version for the local_scan API.
+
+Runtime:
+
+ * smtp transport option hosts_try_fastopen defaults to "*".
+
+ * DNSSec is requested (not required) for all queries. (This seemes to
+ ask for trouble if your resolver is a systemd-resolved.)
+
+ * Generic router option retry_use_local_part defaults to "true" under specific
+ pre-conditions.
+
+ * Introduce a tainting mechanism for values read from untrusted sources.
+
+ * Use longer file names for temporary spool files (this avoids
+ name conflicts with spool on a shared file system).
+
+ * Use dsn_from main config option (was ignored previously).
+
+
+Exim version 4.92
+-----------------
+
+ * Exim used to manually follow CNAME chains, to a limited depth. In this
+ day-and-age we expect the resolver to be doing this for us, so the loop
+ is limited to one retry unless the (new) config option dns_cname_loops
+ is changed.
+
+Exim version 4.91
+-----------------
+
+ * DANE and SPF have been promoted from Experimental to Supported status, thus
+ the options to enable them in Local/Makefile have been renamed.
+ See current src/EDITME for full details, including changes in dependencies,
+ but loosely: replace EXPERIMENTAL_SPF with SUPPORT_SPF and replace
+ EXPERIMENTAL_DANE with SUPPORT_DANE.
+
+ * Ancient ClamAV stream support, long deprecated by ClamAV, has been removed;
+ if you were building with WITH_OLD_CLAMAV_STREAM enabled then your problems
+ have marginally increased.
+
+ * A number of logging changes; if relying upon the previous DKIM additional
+ log-line, explicit log_selector configuration is needed to keep it.
+
+ * Other incompatible changes in EXPERIMENTAL_* features, read NewStuff and
+ ChangeLog carefully if relying upon an experimental feature such as DMARC.
+ Note that this includes changes to SPF as it was promoted into Supported.
+
+
+Exim version 4.89
+-----------------
+
+ * SMTP CHUNKING in Exim 4.88 did not ensure that received mails had a final
+ newline; attempts to deliver such messages onwards to non-chunking hosts
+ would probably hang, as Exim does not insert the newline before a ".".
+ In 4.89, the newline is added upon receipt. For already-received messages
+ in your queue, try util/chunking_fixqueue_finalnewlines.pl
+ to walk the queue, fixing any affected messages. Note that because a
+ delivery attempt will be hanging, attempts to lock the messages for fixing
+ them will stall; stopping all queue-runners temporarily is recommended.
+
+ * OpenSSL: oldest supported release series is now 1.0.2, which is the oldest
+ supported by the OpenSSL project. If you can build Exim with an older
+ release series, congratulations. If you can't, then upgrade.
+ The file doc/openssl.txt contains instructions for installing a current
+ OpenSSL outside the system library paths and building Exim to use it.
+
+ * FreeBSD: we now always use the system iconv in libc, as all versions of
+ FreeBSD supported by the FreeBSD project provide this functionality.
+
+
+Exim version 4.88
+-----------------
+
+ * The "demime" ACL condition, deprecated for the past 10 years, has
+ now been removed.
+
+ * Old GnuTLS configuration options "gnutls_require_kx", "gnutls_require_mac",
+ and "gnutls_require_protocols" have now been removed. (Inoperative from
+ 4.80, per below; logging warnings since 4.83, again per below).
+
+
+Exim version 4.83
+-----------------
+
+ * SPF condition results renamed "permerror" and "temperror". The old
+ names are still accepted for back-compatibility, for this release.
+
+ * TLS details are now logged on rejects, subject to log selectors.
+
+ * Items in headers_remove lists must now have any embedded list-separators
+ doubled.
+
+ * Attempted use of the deprecated options "gnutls_require_kx" et. al.
+ now result in logged warning.
+
+
+Exim version 4.82
+-----------------
+
+ * New option gnutls_allow_auto_pkcs11 defaults false; if you have GnuTLS 2.12.0
+ or later and do want PKCS11 modules to be autoloaded, then set this option.
+
+ * A per-transport wait-<name> database is no longer updated if the transport
+ sets "connection_max_messages" to 1, as it can not be used and causes
+ unnecessary serialisation and load. External tools tracking the state of
+ Exim by the hints databases may need modification to take this into account.
+
+ * The av_scanner option can now accept multiple clamd TCP targets, all other
+ setting limitations remain.
+
+
+Exim version 4.80
+-----------------
+
+ * BEWARE backwards-incompatible changes in SSL libraries, thus the version
+ bump. See points below for details.
+ Also an LDAP data returned format change.
+
+ * The value of $tls_peerdn is now print-escaped when written to the spool file
+ in a -tls_peerdn line, and unescaped when read back in. We received reports
+ of values with embedded newlines, which caused spool file corruption.
+
+ If you have a corrupt spool file and you wish to recover the contents after
+ upgrading, then lock the message, replace the new-lines that should be part
+ of the -tls_peerdn line with the two-character sequence \n and then unlock
+ the message. No tool has been provided as we believe this is a rare
+ occurrence.
+
+ * For OpenSSL, SSLv2 is now disabled by default. (GnuTLS does not support
+ SSLv2). RFC 6176 prohibits SSLv2 and some informal surveys suggest no
+ actual usage. You can re-enable with the "openssl_options" Exim option,
+ in the main configuration section. Note that supporting SSLv2 exposes
+ you to ciphersuite downgrade attacks.
+
+ * With OpenSSL 1.0.1+, Exim now supports TLS 1.1 and TLS 1.2. If built
+ against 1.0.1a then you will get a warning message and the
+ "openssl_options" value will not parse "no_tlsv1_1": the value changes
+ incompatibly between 1.0.1a and 1.0.1b, because the value chosen for 1.0.1a
+ is infelicitous. We advise avoiding 1.0.1a.
+
+ "openssl_options" gains "no_tlsv1_1", "no_tlsv1_2" and "no_compression".
+
+ COMPATIBILITY WARNING: The default value of "openssl_options" is no longer
+ "+dont_insert_empty_fragments". We default to "+no_sslv2".
+ That old default was grandfathered in from before openssl_options became a
+ configuration option.
+ Empty fragments are inserted by default through TLS1.0, to partially defend
+ against certain attacks; TLS1.1+ change the protocol so that this is not
+ needed. The DIEF SSL option was required for some old releases of mail
+ clients which did not gracefully handle the empty fragments, and was
+ initially set in Exim release 4.31 (see ChangeLog, item 37).
+
+ If you still have affected mail-clients, and you see SSL protocol failures
+ with this release of Exim, set:
+ openssl_options = +dont_insert_empty_fragments
+ in the main section of your Exim configuration file. You're trading off
+ security for compatibility. Exim is now defaulting to higher security and
+ rewarding more modern clients.
+
+ If the option tls_dhparams is set and the parameters loaded from the file
+ have a bit-count greater than the new option tls_dh_max_bits, then the file
+ will now be ignored. If this affects you, raise the tls_dh_max_bits limit.
+ We suspect that most folks are using dated defaults and will not be affected.
+
+ * Ldap lookups returning multi-valued attributes now separate the attributes
+ with only a comma, not a comma-space sequence. Also, an actual comma within
+ a returned attribute is doubled. This makes it possible to parse the
+ attribute as a comma-separated list. Note the distinction from multiple
+ attributes being returned, where each one is a name=value pair.
+
+ If you are currently splitting the results from LDAP upon a comma, then you
+ should check carefully to see if adjustments are needed.
+
+ This change lets cautious folks distinguish "comma used as separator for
+ joining values" from "comma inside the data".
+
+ * accept_8bitmime now defaults on, which is not RFC compliant but is better
+ suited to today's Internet. See http://cr.yp.to/smtp/8bitmime.html for a
+ sane rationale. Those who wish to be strictly RFC compliant, or know that
+ they need to talk to servers that are not 8-bit-clean, now need to take
+ explicit configuration action to default this option off. This is not a
+ new option, you can safely force it off before upgrading, to decouple
+ configuration changes from the binary upgrade while remaining RFC compliant.
+
+ * The GnuTLS support has been mostly rewritten, to use APIs which don't cause
+ deprecation warnings in GnuTLS 2.12.x. As part of this, these three options
+ are no longer supported:
+
+ gnutls_require_kx
+ gnutls_require_mac
+ gnutls_require_protocols
+
+ Their functionality is entirely subsumed into tls_require_ciphers. In turn,
+ tls_require_ciphers is no longer an Exim list and is not parsed by Exim, but
+ is instead given to gnutls_priority_init(3), which expects a priority string;
+ this behaviour is much closer to the OpenSSL behaviour. See:
+
+ http://www.gnutls.org/manual/html_node/Priority-Strings.html
+
+ for fuller documentation of the strings parsed. The three gnutls_require_*
+ options are still parsed by Exim and, for this release, silently ignored.
+ A future release will add warnings, before a later still release removes
+ parsing entirely and the presence of the options will be a configuration
+ error.
+
+ Note that by default, GnuTLS will not accept RSA-MD5 signatures in chains.
+ A tls_require_ciphers value of NORMAL:%VERIFY_ALLOW_SIGN_RSA_MD5 may
+ re-enable support, but this is not supported by the Exim maintainers.
+ Our test suite no longer includes MD5-based certificates.
+
+ This rewrite means that Exim will continue to build against GnuTLS in the
+ future, brings Exim closer to other GnuTLS applications and lets us add
+ support for SNI and other features more readily. We regret that it wasn't
+ feasible to retain the three dropped options.
+
+ * If built with TLS support, then Exim will now validate the value of
+ the main section tls_require_ciphers option at start-up. Before, this
+ would cause a STARTTLS 4xx failure, now it causes a failure to start.
+ Running with a broken configuration which causes failures that may only
+ be left in the logs has been traded off for something more visible. This
+ change makes an existing problem more prominent, but we do not believe
+ anyone would deliberately be running with an invalid tls_require_ciphers
+ option.
+
+ This also means that library linkage issues caused by conflicts of some
+ kind might take out the main daemon, not just the delivery or receiving
+ process. Conceivably some folks might prefer to continue delivering
+ mail plaintext when their binary is broken in this way, if there is a
+ server that is a candidate to receive such mails that does not advertise
+ STARTTLS. Note that Exim is typically a setuid root binary and given
+ broken linkage problems that cause segfaults, we feel it is safer to
+ fail completely. (The check is not done as root, to ensure that problems
+ here are not made worse by the check).
+
+ * The "tls_dhparam" option has been updated, so that it can now specify a
+ path or an identifier for a standard DH prime from one of a few RFCs.
+ The default for OpenSSL is no longer to not use DH but instead to use
+ one of these standard primes. The default for GnuTLS is no longer to use
+ a file in the spool directory, but to use that same standard prime.
+ The option is now used by GnuTLS too. If it points to a path, then
+ GnuTLS will use that path, instead of a file in the spool directory;
+ GnuTLS will attempt to create it if it does not exist.
+
+ To preserve the previous behaviour of generating files in the spool
+ directory, set "tls_dhparam = historic". Since prior releases of Exim
+ ignored tls_dhparam when using GnuTLS, this can safely be done before
+ the upgrade.
+
+
+
+Exim version 4.77
+-----------------
+
+ * GnuTLS will now attempt to use TLS 1.2 and TLS 1.1 before TLS 1.0 and SSL3,
+ if supported by your GnuTLS library. Use the existing
+ "gnutls_require_protocols" option to downgrade this if that will be a
+ problem. Prior to this release, supported values were "TLS1" and "SSL3",
+ so you should be able to update configuration prior to update.
+
+ [nb: gnutls_require_protocols removed in Exim 4.80, instead use
+ tls_require_ciphers to provide a priority string; see notes above]
+
+ * The match_<type>{string1}{string2} expansion conditions no longer subject
+ string2 to string expansion, unless Exim was built with the new
+ "EXPAND_LISTMATCH_RHS" option. Too many people have inadvertently created
+ insecure configurations that way. If you need the functionality and turn on
+ that build option, please let the developers know, and know why, so we can
+ try to provide a safer mechanism for you.
+
+ The match{}{} expansion condition (for regular expressions) is NOT affected.
+ For match_<type>{s1}{s2}, all list functionality is unchanged. The only
+ change is that a '$' appearing in s2 will not trigger expansion, but instead
+ will be treated as a literal $ sign; the effect is very similar to having
+ wrapped s2 with \N...\N. If s2 contains a named list and the list definition
+ uses $expansions then those _will_ be processed as normal. It is only the
+ point at which s2 is read where expansion is inhibited.
+
+ If you are trying to test if two email addresses are equal, use eqi{s1}{s2}.
+ If you are testing if the address in s1 occurs in the list of items given
+ in s2, either use the new inlisti{s1}{s2} condition (added in 4.77) or use
+ the pre-existing forany{s2}{eqi{$item}{s1}} condition.
+
+
+Exim version 4.74
+-----------------
+
+ * The integrated support for dynamically loadable lookup modules has an ABI
+ change from the modules supported by some OS vendors through an unofficial
+ patch. Don't try to mix & match.
+
+ * Some parts of the build system are now beginning to assume that the host
+ environment is POSIX. If you're building on a system where POSIX tools are
+ not the default, you might have an easier time if you switch to the POSIX
+ tools. Feel free to report non-POSIX issues as a request for a feature
+ enhancement, but if the POSIX variants are available then the fix will
+ probably just involve some coercion. See the README instructions for
+ building on such hosts.
+
+
+Exim version 4.73
+-----------------
+
+ * The Exim run-time user can no longer be root; this was always
+ strongly discouraged, but is now prohibited both at build and
+ run-time. If you need Exim to run routinely as root, you'll need to
+ patch the source and accept the risk. Here be dragons.
+
+ * Exim will no longer accept a configuration file owned by the Exim
+ run-time user, unless that account is explicitly the value in
+ CONFIGURE_OWNER, which we discourage. Exim now checks to ensure that
+ files are not writeable by other accounts.
+
+ * The ALT_CONFIG_ROOT_ONLY build option is no longer optional and is forced
+ on; the Exim user can, by default, no longer use -C/-D and retain privilege.
+ Two new build options mitigate this.
+
+ * TRUSTED_CONFIG_LIST defines a file containing a whitelist of config
+ files that are trusted to be selected by the Exim user; one per line.
+ This is the recommended approach going forward.
+
+ * WHITELIST_D_MACROS defines a colon-separated list of macro names which
+ the Exim run-time user may safely pass without dropping privileges.
+ Because changes to this involve a recompile, this is not the recommended
+ approach but may ease transition. The values of the macros, when
+ overridden, are constrained to match this regex: ^[A-Za-z0-9_/.-]*$
+
+ * The system_filter_user option now defaults to the Exim run-time user,
+ rather than root. You can still set it explicitly to root and this
+ can be done with prior versions too, letting you roll versions
+ without needing to change this configuration option.
+
+ * ClamAV must be at least version 0.95 unless WITH_OLD_CLAMAV_STREAM is
+ defined at build time.
+
+
+Exim version 4.70
+-----------------
+
+1. Experimental Yahoo! Domainkeys support has been dropped in this release.
+It has been superseded by a native implementation of its successor DKIM.
+
+2. Up to version 4.69, Exim came with an embedded version of the PCRE library.
+As of 4.70, this is no longer the case. To compile Exim, you will need PCRE
+installed. Most OS distributions have ready-made library and development
+packages.
+
+
+Exim version 4.68
+-----------------
+
+1. The internal implementation of the database keys that are used for ACL
+ratelimiting has been tidied up. This means that an update to 4.68 might cause
+Exim to "forget" previous rates that it had calculated, and reset them to zero.
+
+
+Exim version 4.64
+-----------------
+
+1. Callouts were setting the name used for EHLO/HELO from $smtp_active_
+hostname. This is wrong, because it relates to the incoming message (and
+probably the interface on which it is arriving) and not to the outgoing
+callout (which could be using a different interface). This has been
+changed to use the value of the helo_data option from the smtp transport
+instead - this is what is used when a message is actually being sent. If
+there is no remote transport (possible with a router that sets up host
+addresses), $smtp_active_hostname is used. This change is mentioned here in
+case somebody is relying on the use of $smtp_active_hostname.
+
+2. A bug has been fixed that might just possibly be something that is relied on
+in some configurations. In expansion items such as ${if >{xxx}{yyy}...} an
+empty string (that is {}) was being interpreted as if it was {0} and therefore
+treated as the number zero. From release 4.64, such strings cause an error
+because a decimal number, possibly followed by K or M, is required (as has
+always been documented).
+
+3. There has been a change to the GnuTLS support (ChangeLog/PH/20) to improve
+Exim's performance. Unfortunately, this has the side effect of being slightly
+non-upwards compatible for versions 4.50 and earlier. If you are upgrading from
+one of these earlier versions and you use GnuTLS, you must remove the file
+called gnutls-params in Exim's spool directory. If you don't do this, you will
+see this error:
+
+ TLS error on connection from ... (DH params import): Base64 decoding error.
+
+Removing the file causes Exim to recompute the relevant encryption parameters
+and cache them in the new format that was introduced for release 4.51 (May
+2005). If you are upgrading from release 4.51 or later, there should be no
+problem.
+
+
+Exim version 4.63
+-----------------
+
+When an SMTP error message is specified in a "message" modifier in an ACL, or
+in a :fail: or :defer: message in a redirect router, Exim now checks the start
+of the message for an SMTP error code. This consists of three digits followed
+by a space, optionally followed by an extended code of the form n.n.n, also
+followed by a space. If this is the case and the very first digit is the same
+as the default error code, the code from the message is used instead. If the
+very first digit is incorrect, a panic error is logged, and the default code is
+used. This is an incompatible change, but it is not expected to affect many (if
+any) configurations. It is possible to suppress the use of the supplied code in
+a redirect router by setting the smtp_error_code option false. In this case,
+any SMTP code is quietly ignored.
+
+
+Exim version 4.61
+-----------------
+
+1. The default number of ACL variables of each type has been increased to 20,
+and it's possible to compile Exim with more. You can safely upgrade to this
+release if you already have messages on the queue with saved ACL variable
+values. However, if you downgrade from this release with messages on the queue,
+any saved ACL values they may have will be lost.
+
+2. The default value for rfc1413_query_timeout has been changed from 30s to 5s.
+
+
+Exim version 4.54
+-----------------
+
+There was a problem with 4.52/TF/02 in that a "name=" option on control=
+submission terminated at the next slash, thereby not allowing for slashes in
+the name. This has been changed so that "name=" takes the rest of the string as
+its data. It must therefore be the last option.
+
+
+Version 4.53
+------------
+
+If you are using the experimental Domain Keys support, you must upgrade to
+at least libdomainkeys 0.67 in order to run this release of Exim.
+
+
+Version 4.51
+------------
+
+1. The format in which GnuTLS parameters are cached (in the file gnutls-params
+in the spool directory) has been changed. The new format can also be generated
+externally, so it is now possible to update the values from outside Exim. This
+has been implemented in an upwards, BUT NOT downwards, compatible manner.
+Upgrading should be seamless: when Exim finds that it cannot understand an
+existing cache file, it generates new parameters and writes them to the cache
+in the new format. If, however, you downgrade from 4.51 to a previous release,
+you MUST delete the gnutls-params file in the spool directory, because the
+older Exim will not recognize the new format.
+
+2. When doing a callout as part of verifying an address, Exim was not paying
+attention to any local part prefix or suffix that was matched by the router
+that accepted the address. It now behaves in the same way as it does for
+delivery: the affixes are removed from the local part unless
+rcpt_include_affixes is set on the transport. If you have a configuration that
+uses prefixes or suffixes on addresses that could be used for callouts, and you
+want the affixes to be retained, you must make sure that rcpt_include_affixes
+is set on the transport.
+
+3. Bounce and delay warning messages no longer contain details of delivery
+errors, except for explicit messages (e.g. generated by :fail:) and SMTP
+responses from remote hosts.
+
+
+Version 4.50
+------------
+
+The exicyclog script has been updated to use three-digit numbers in rotated log
+files if the maximum number to keep is greater than 99. If you are already
+keeping more than 99, there will be an incompatible change when you upgrade.
+You will probably want to rename your old log files to the new form before
+running the new exicyclog.
+
+
+Version 4.42
+------------
+
+RFC 3848 specifies standard names for the "with" phrase in Received: header
+lines when AUTH and/or TLS are in use. This is the "received protocol"
+field. Exim used to use "asmtp" for authenticated SMTP, without any
+indication (in the protocol name) for TLS use. Now it follows the RFC and
+uses "esmtpa" if the connection is authenticated, "esmtps" if it is
+encrypted, and "esmtpsa" if it is both encrypted and authenticated. These names
+appear in log lines as well as in Received: header lines.
+
+
+Version 4.34
+------------
+
+Change 4.31/2 gave problems to data ACLs and local_scan() functions that
+expected to see a Received: header. I have changed to yet another scheme. The
+Received: header is now generated after the body is received, but before the
+ACL or local_scan() is called. After they have run, the timestamp in the
+Received: header is updated.
+
+Thus, change (a) of 4.31/2 has been reversed, but change (b) is still true,
+which is lucky, since I decided it was a bug fix.
+
+
+Version 4.33
+------------
+
+If an expansion in a condition on a "warn" statement fails because a lookup
+defers, the "warn" statement is abandoned, and the next ACL statement is
+processed. Previously this caused the whole ACL to be aborted.
+
+
+Version 4.32
+------------
+
+Change 4.31/2 has been reversed, as it proved contentious. Recipient callout
+verification now uses <> in the MAIL command by default, as it did before. A
+new callout option, "use_sender", has been added to request the other
+behaviour.
+
+
+Version 4.31
+------------
+
+1. If you compile Exim to use GnuTLS, it now requires the use of release 1.0.0
+ or greater. The interface to the obsolete 0.8.x releases is no longer
+ supported. There is one externally visible change: the format for the
+ display of Distinguished Names now uses commas as a separator rather than a
+ slash. This is to comply with RFC 2253.
+
+2. When a message is received, the Received: header line is now generated when
+ reception is complete, instead of at the start of reception. For messages
+ that take a long time to come in, this changes the meaning of the timestamp.
+ There are several side-effects of this change:
+
+ (a) If a message is rejected by a DATA or non-SMTP ACL, or by local_scan(),
+ the logged header lines no longer include the local Received: line,
+ because it has not yet been created. If the message is a non-SMTP one,
+ and the error is processed by sending a message to the sender, the copy
+ of the original message that is returned does not have an added
+ Received: line.
+
+ (b) When a filter file is tested using -bf, no additional Received: header
+ is added to the test message. After some thought, I decided that this
+ is a bug fix.
+
+ The contents of $received_for are not affected by this change. This
+ variable still contains the single recipient of a message, copied after
+ addresses have been rewritten, but before local_scan() is run.
+
+2. Recipient callout verification, like sender verification, was using <> in
+ the MAIL FROM command. This isn't really the right thing, since the actual
+ sender may affect whether the remote host accepts the recipient or not. I
+ have changed it to use the actual sender in the callout; this means that
+ the cache record is now keyed on a recipient/sender pair, not just the
+ recipient address. There doesn't seem to be a real danger of callout loops,
+ since a callout by the remote host to check the sender would use <>.
+
+
+Version 4.30
+------------
+
+1. I have abolished timeout_DNS as an error that can be detected in retry
+ rules, because it has never worked. Despite the fact that it has been
+ documented since at least release 1.62, there was no code to support it.
+ If you have used it in your retry rules, you will now get a warning message
+ to the log and panic log. It is now treated as plain "timeout".
+
+2. After discussion on the mailing list, Exim no longer adds From:, Date:, or
+ Message-Id: header lines to messages that do not originate locally, that is,
+ messages that have an associated sending host address.
+
+3. When looking up a host name from an IP address, Exim now tries the DNS
+ first, and only if that fails does it use gethostbyaddr() (or equivalent).
+ This change was made because on some OS, not all the names are given for
+ addresses with multiple PTR records via the gethostbyaddr() interface. The
+ order of lookup can be changed by setting host_lookup_order.
+
+
+Version 4.23
+------------
+
+1. The new FIXED_NEVER_USERS build-time option creates a list of "never users"
+ that cannot be overridden. The default in the distributed EDITME is "root".
+ If for some reason you were (against advice) running deliveries as root, you
+ will have to ensure that FIXED_NEVER_USERS is not set in your
+ Local/Makefile.
+
+2. The ${quote: operator now quotes an empty string, which it did not before.
+
+3. Version 4.23 saves the contents of the ACL variables with the message, so
+ that they can be used later. If one of these variables contains a newline,
+ there will be a newline character in the spool that will not be interpreted
+ correctly by a previous version of Exim. (Exim ignores keyed spool file
+ items that it doesn't understand - precisely for this kind of problem - but
+ it expects them all to be on one line.)
+
+ So the bottom line is: if you have newlines in your ACL variables, you
+ cannot retreat from 4.23.
+
+
+Version 4.21
+------------
+
+1. The idea of the "warn" ACL verb is that it adds a header or writes to the
+ log only when "message" or "log_message" are set. However, if one of the
+ conditions was an address verification, or a call to a nested ACL, the
+ messages generated by the underlying test were being passed through. This
+ no longer happens. The underlying message is available in $acl_verify_
+ message for both "message" and "log_message" expansions, so it can be
+ passed through if needed.
+
+2. The way that the $h_ (and $header_) expansions work has been changed by the
+ addition of RFC 2047 decoding. See the main documentation (the NewStuff file
+ until release 4.30, then the manual) for full details. Briefly, there are
+ now three forms:
+
+ $rh_xxx: and $rheader_xxx: give the original content of the header
+ line(s), with no processing at all.
+
+ $bh_xxx: and $bheader_xxx: remove leading and trailing white space, and
+ then decode base64 or quoted-printable "words" within the header text,
+ but do not do charset translation.
+
+ $h_xxx: and $header_xxx: attempt to translate the $bh_ string to a
+ standard character set.
+
+ If you have previously been using $h_ expansions to access the raw
+ characters, you should change to $rh_ instead.
+
+3. When Exim creates an RFC 2047 encoded word in a header line, it labels it
+ with the default character set from the headers_charset option instead of
+ always using iso-8859-1.
+
+4. If TMPDIR is defined in Local/Makefile (default in src/EDITME is
+ TMPDIR="/tmp"), Exim checks for the presence of an environment variable
+ called TMPDIR, and if it finds it is different, it changes its value.
+
+5. Following a discussion on the list, the rules by which Exim recognises line
+ endings on incoming messages have been changed. The -dropcr and drop_cr
+ options are now no-ops, retained only for backwards compatibility. The
+ following line terminators are recognized: LF CRLF CR. However, special
+ processing applies to CR:
+
+ (i) The sequence CR . CR does *not* terminate an incoming SMTP message,
+ nor a local message in the state where . is a terminator.
+
+ (ii) If a bare CR is encountered in a header line, an extra space is added
+ after the line terminator so as not to end the header. The reasoning
+ behind this is that bare CRs in header lines are most likely either
+ to be mistakes, or people trying to play silly games.
+
+6. The code for using daemon_smtp_port, local_interfaces, and the -oX options
+ has been reorganized. It is supposed to be backwards compatible, but it is
+ mentioned here just in case I've screwed up.
+
+
+
+Version 4.20
+------------
+
+1. I have tidied and re-organized the code that uses alarm() for imposing time
+ limits on various things. It shouldn't affect anything, but if you notice
+ processes getting stuck, it may be that I've broken something.
+
+2. The "arguments" log selector now also logs the current working directory
+ when Exim is called.
+
+3. An incompatible change has been made to the appendfile transport. This
+ affects the case when it is used for file deliveries that are set up by
+ .forward and filter files. Previously, any settings of the "file" or
+ "directory" options were ignored. It is hoped that, like the address_file
+ transport in the default configuration, these options were never in fact set
+ on such transports, because they were of no use.
+
+ Now, if either of these options is set, it is used. The path that is passed
+ by the router is in $address_file (this is not new), so it can be used as
+ part of a longer path, or modified in any other way that expansion permits.
+
+ If neither "file" nor "directory" is set, the behaviour is unchanged.
+
+4. Related to the above: in a filter, if a "save" command specifies a non-
+ absolute path, the value of $home/ is pre-pended. This no longer happens if
+ $home is unset or is set to an empty string.
+
+5. Multiple file deliveries from a filter or .forward file can never be
+ batched; the value of batch_max on the transport is ignored for file
+ deliveries. I'm assuming that nobody ever actually set batch_max on the
+ address_file transport - it would have had odd effects previously.
+
+6. DESTDIR is the more common variable that ROOT for use when installing
+ software under a different root filing system. The Exim install script now
+ recognizes DESTDIR first; if it is not set, ROOT is used.
+
+7. If DESTDIR is set when installing Exim, it no longer prepends its value to
+ the path of the system aliases file that appears in the default
+ configuration (when a default configuration is installed). If an aliases
+ file is actually created, its name *does* use the prefix.
+
+
+Version 4.14
+------------
+
+1. The default for the maximum number of unknown SMTP commands that Exim will
+accept before dropping a connection has been reduced from 5 to 3. However, you
+can now change the value by setting smtp_max_unknown_commands.
+
+2. The ${quote: operator has been changed so that it turns newline and carriage
+return characters into \n and \r, respectively.
+
+3. The file names used for maildir messages now include the microsecond time
+fraction as well as the time in seconds, to cope with systems where the process
+id can be re-used within the same second. The format is now
+
+ <time>.H<microsec>P<pid>.<host>
+
+This should be a compatible change, but is noted here just in case.
+
+4. The rules for creating message ids have changed, to cope with systems where
+the process id can be re-used within the same second. The format, however, is
+unchanged, so this should not cause any problems, except as noted in the next
+item.
+
+5. The maximum value for localhost_number has been reduced from 255 to 16, in
+order to implement the new message id rules. For operating systems that have
+case-insensitive file systems (Cygwin and Darwin), the limit is 10.
+
+6. verify = header_syntax was allowing unqualified addresses in all cases. Now
+it allows them only for locally generated messages and from hosts that match
+sender_unqualified_hosts or recipient_unqualified_hosts, respectively.
+
+7. For reasons lost in the mists of time, when a pipe transport was run, the
+environment variable MESSAGE_ID was set to the message ID preceded by 'E' (the
+form used in Message-ID: header lines). The 'E' has been removed.
+
+
+Version 4.11
+------------
+
+1. The handling of lines in the configuration file has changed. Previously,
+macro expansion was applied to logical lines, after continuations had been
+joined on. This meant that it could not be used in .include lines, which are
+handled as physical rather than logical lines. Macro expansion is now done on
+physical lines rather than logical lines. This means there are two
+incompatibilities:
+
+ (a) A macro that expands to # to turn a line into a comment now applies only
+ to the physical line where it appears. Previously, it would have caused
+ any following continuations also to be ignored.
+
+ (b) A macro name can no longer be split over the boundary between a line and
+ its continuation. Actually, this is more of a bug fix. :-)
+
+2. The -D command line option must now all be within one command line item.
+This makes it possible to use -D to set a macro to the empty string by commands
+such as
+
+ exim -DABC ...
+ exim -DABC= ...
+
+Previously, these items would have moved on to the next item on the command
+line. To include spaces in a macro definition item, quotes must be used, in
+which case you can also have spaces after -D and surrounding the equals. For
+example:
+
+ exim '-D ABC = something' ...
+
+3. The way that addresses that redirect to themselves are handled has been
+changed, in order to fix an obscure bug. This should not cause any problems
+except in the case of wanting to go back from a 4.11 (or later) release to an
+earlier release. If there are undelivered messages on the spool that contain
+addresses which redirect to themselves, and the redirected addresses have
+already been delivered, you might get a duplicate delivery if you revert to an
+earlier Exim.
+
+4. The default way of looking up IP addresses for hosts in the manualroute and
+queryprogram routers has been changed. If "byname" or "bydns" is explicitly
+specified, there is no change, but if no method is specified, Exim now behaves
+as follows:
+
+ First, a DNS lookup is done. If this yields anything other than
+ HOST_NOT_FOUND, that result is used. Otherwise, Exim goes on to try a call to
+ getipnodebyname() (or gethostbyname() on older systems) and the result of the
+ lookup is the result of that call.
+
+This change has been made because it has been discovered that on some systems,
+if a DNS lookup called via getipnodebyname() times out, HOST_NOT_FOUND is
+returned instead of TRY_AGAIN. Thus, it is safest to try a DNS lookup directly
+first, and only if that gives a definite "no such host" to try the local
+function.
+
+5. In fixing the minor security problem with pid_file_path, I have removed some
+backwards-compatible (undocumented) code which was present to ease conversion
+from Exim 3. In Exim 4, pid_file_path is a literal; in Exim 3 it was allowed to
+contain "%s", which was replaced by the port number for daemons listening on
+non-standard ports. In Exim 4, such daemons do not write a pid file. The
+backwards compatibility feature was to replace "%s" by nothing if it occurred
+in an Exim 4 setting of pid_file_path. The bug was in this code. I have solved
+the problem by removing the backwards compatibility feature. Thus, if you still
+have "%s" somewhere in a setting of pid_file_path, you should remove it.
+
+6. There has been an extension to lsearch files. The keys in these files may
+now be quoted in order to allow for whitespace and colons in them. This means
+that if you were previously using keys that began with a doublequote, you will
+now have to wrap them with extra quotes and escape the internal quotes. The
+possibility that anybody is actually doing this seems extremely remote, but it
+is documented just in case.
+
+
+Version 4.10
+------------
+
+The build-time parameter EXIWHAT_KILL_ARG has been renamed EXIWHAT_KILL_SIGNAL
+to better reflect its function. The OS-specific files have been updated. Only
+if you have explicitly set this in your Makefile (highly unlikely) do you need
+to change anything.
+
+****