1 This document contains detailed information about incompatibilities that might
2 be encountered when upgrading from one release of Exim to another. The
3 information is in reverse order of release numbers. Mostly these are relatively
4 small points, and the configuration file is normally upwards compatible, but
5 there have been two big upheavals...
8 **************************************************************************
9 * There was a big reworking of the way mail routing works for release *
10 * 4.00. Previously used "directors" were abolished, and all routing is *
11 * now done by routers. Policy controls for incoming mail are now done by *
12 * Access Control Lists instead of separate options. All this means that *
13 * pre-4.00 configuration files have to be massively converted. If you *
14 * are coming from a 3.xx release, please read the document in the file *
15 * doc/Exim4.upgrade, and allow some time to complete the upgrade. *
17 * There was a big reworking of the way domain/host/net/address lists are *
18 * handled at release 3.00. If you are coming from a pre-3.00 release, it *
19 * might be easier to start again from a default configuration. Otherwise *
20 * you need to read doc/Exim3.upgrade and do a double conversion of your *
21 * configuration file. *
22 **************************************************************************
25 The rest of this document contains information about changes in 4.xx releases
26 that might affect a running system.
32 * The value of $tls_peerdn is now print-escaped when written to the spool file
33 in a -tls_peerdn line, and unescaped when read back in. We received reports
34 of values with embedded newlines, which caused spool file corruption.
36 If you have a corrupt spool file and you wish to recover the contents after
37 upgrading, then lock the message, replace the new-lines that should be part
38 of the -tls_peerdn line with the two-character sequence \n and then unlock
39 the message. No tool has been provided as we believe this is a rare
42 * For OpenSSL, SSLv2 is now disabled by default. (GnuTLS does not support
43 SSLv2). RFC 6176 prohibits SSLv2 and some informal surveys suggest no
44 actual usage. You can re-enable with the "openssl_options" Exim option,
45 in the main configuration section. Note that supporting SSLv2 exposes
46 you to ciphersuite downgrade attacks.
48 * With OpenSSL 1.0.1+, Exim now supports TLS 1.1 and TLS 1.2. If built
49 against 1.0.1a then you will get a warning message and the
50 "openssl_options" value will not parse "no_tlsv1_1": the value changes
51 incompatibly between 1.0.1a and 1.0.1b, because the value chosen for 1.0.1a
52 is infelicitous. We advise avoiding 1.0.1a.
54 "openssl_options" gains "no_tlsv1_1", "no_tlsv1_2" and "no_compression".
56 COMPATIBILITY WARNING: The default value of "openssl_options" is no longer
57 "+dont_insert_empty_fragments". We default to "+no_sslv2".
58 That old default was grandfathered in from before openssl_options became a
60 Empty fragments are inserted by default through TLS1.0, to partially defend
61 against certain attacks; TLS1.1+ change the protocol so that this is not
62 needed. The DIEF SSL option was required for some old releases of mail
63 clients which did not gracefully handle the empty fragments, and was
64 initially set in Exim release 4.31 (see ChangeLog, item 37).
66 If you still have affected mail-clients, and you see SSL protocol failures
67 with this release of Exim, set:
68 openssl_options = +dont_insert_empty_fragments
69 in the main section of your Exim configuration file. You're trading off
70 security for compatibility. Exim is now defaulting to higher security and
71 rewarding more modern clients.
73 * Ldap lookups returning multi-valued attributes now separate the attributes
74 with only a comma, not a comma-space sequence. Also, an actual comma within
75 a returned attribute is doubled. This makes it possible to parse the
76 attribute as a comma-separated list. Note the distinction from multiple
77 attributes being returned, where each one is a name=value pair.
83 * GnuTLS will now attempt to use TLS 1.2 and TLS 1.1 before TLS 1.0 and SSL3,
84 if supported by your GnuTLS library. Use the existing
85 "gnutls_require_protocols" option to downgrade this if that will be a
86 problem. Prior to this release, supported values were "TLS1" and "SSL3",
87 so you should be able to update configuration prior to update.
89 * The match_<type>{string1}{string2} expansion conditions no longer subject
90 string2 to string expansion, unless Exim was built with the new
91 "EXPAND_LISTMATCH_RHS" option. Too many people have inadvertently created
92 insecure configurations that way. If you need the functionality and turn on
93 that build option, please let the developers know, and know why, so we can
94 try to provide a safer mechanism for you.
96 The match{}{} expansion condition (for regular expressions) is NOT affected.
97 For match_<type>{s1}{s2}, all list functionality is unchanged. The only
98 change is that a '$' appearing in s2 will not trigger expansion, but instead
99 will be treated as a literal $ sign; the effect is very similar to having
100 wrapped s2 with \N...\N. If s2 contains a named list and the list definition
101 uses $expansions then those _will_ be processed as normal. It is only the
102 point at which s2 is read where expansion is inhibited.
104 If you are trying to test if two email addresses are equal, use eqi{s1}{s2}.
105 If you are testing if the address in s1 occurs in the list of items given
106 in s2, either use the new inlisti{s1}{s2} condition (added in 4.77) or use
107 the pre-existing forany{s2}{eqi{$item}{s1}} condition.
113 * The integrated support for dynamically loadable lookup modules has an ABI
114 change from the modules supported by some OS vendors through an unofficial
115 patch. Don't try to mix & match.
117 * Some parts of the build system are now beginning to assume that the host
118 environment is POSIX. If you're building on a system where POSIX tools are
119 not the default, you might have an easier time if you switch to the POSIX
120 tools. Feel free to report non-POSIX issues as a request for a feature
121 enhancement, but if the POSIX variants are available then the fix will
122 probably just involve some coercion. See the README instructions for
123 building on such hosts.
129 * The Exim run-time user can no longer be root; this was always
130 strongly discouraged, but is now prohibited both at build and
131 run-time. If you need Exim to run routinely as root, you'll need to
132 patch the source and accept the risk. Here be dragons.
134 * Exim will no longer accept a configuration file owned by the Exim
135 run-time user, unless that account is explicitly the value in
136 CONFIGURE_OWNER, which we discourage. Exim now checks to ensure that
137 files are not writeable by other accounts.
139 * The ALT_CONFIG_ROOT_ONLY build option is no longer optional and is forced
140 on; the Exim user can, by default, no longer use -C/-D and retain privilege.
141 Two new build options mitigate this.
143 * TRUSTED_CONFIG_LIST defines a file containing a whitelist of config
144 files that are trusted to be selected by the Exim user; one per line.
145 This is the recommended approach going forward.
147 * WHITELIST_D_MACROS defines a colon-separated list of macro names which
148 the Exim run-time user may safely pass without dropping privileges.
149 Because changes to this involve a recompile, this is not the recommended
150 approach but may ease transition. The values of the macros, when
151 overridden, are constrained to match this regex: ^[A-Za-z0-9_/.-]*$
153 * The system_filter_user option now defaults to the Exim run-time user,
154 rather than root. You can still set it explicitly to root and this
155 can be done with prior versions too, letting you roll versions
156 without needing to change this configuration option.
158 * ClamAV must be at least version 0.95 unless WITH_OLD_CLAMAV_STREAM is
159 defined at build time.
165 1. Experimental Yahoo! Domainkeys support has been dropped in this release.
166 It has been superceded by a native implementation of its successor DKIM.
168 2. Up to version 4.69, Exim came with an embedded version of the PCRE library.
169 As of 4.70, this is no longer the case. To compile Exim, you will need PCRE
170 installed. Most OS distributions have ready-made library and development
177 1. The internal implementation of the database keys that are used for ACL
178 ratelimiting has been tidied up. This means that an update to 4.68 might cause
179 Exim to "forget" previous rates that it had calculated, and reset them to zero.
185 1. Callouts were setting the name used for EHLO/HELO from $smtp_active_
186 hostname. This is wrong, because it relates to the incoming message (and
187 probably the interface on which it is arriving) and not to the outgoing
188 callout (which could be using a different interface). This has been
189 changed to use the value of the helo_data option from the smtp transport
190 instead - this is what is used when a message is actually being sent. If
191 there is no remote transport (possible with a router that sets up host
192 addresses), $smtp_active_hostname is used. This change is mentioned here in
193 case somebody is relying on the use of $smtp_active_hostname.
195 2. A bug has been fixed that might just possibly be something that is relied on
196 in some configurations. In expansion items such as ${if >{xxx}{yyy}...} an
197 empty string (that is {}) was being interpreted as if it was {0} and therefore
198 treated as the number zero. From release 4.64, such strings cause an error
199 because a decimal number, possibly followed by K or M, is required (as has
200 always been documented).
202 3. There has been a change to the GnuTLS support (ChangeLog/PH/20) to improve
203 Exim's performance. Unfortunately, this has the side effect of being slightly
204 non-upwards compatible for versions 4.50 and earlier. If you are upgrading from
205 one of these earlier versions and you use GnuTLS, you must remove the file
206 called gnutls-params in Exim's spool directory. If you don't do this, you will
209 TLS error on connection from ... (DH params import): Base64 decoding error.
211 Removing the file causes Exim to recompute the relevant encryption parameters
212 and cache them in the new format that was introduced for release 4.51 (May
213 2005). If you are upgrading from release 4.51 or later, there should be no
220 When an SMTP error message is specified in a "message" modifier in an ACL, or
221 in a :fail: or :defer: message in a redirect router, Exim now checks the start
222 of the message for an SMTP error code. This consists of three digits followed
223 by a space, optionally followed by an extended code of the form n.n.n, also
224 followed by a space. If this is the case and the very first digit is the same
225 as the default error code, the code from the message is used instead. If the
226 very first digit is incorrect, a panic error is logged, and the default code is
227 used. This is an incompatible change, but it is not expected to affect many (if
228 any) configurations. It is possible to suppress the use of the supplied code in
229 a redirect router by setting the smtp_error_code option false. In this case,
230 any SMTP code is quietly ignored.
236 1. The default number of ACL variables of each type has been increased to 20,
237 and it's possible to compile Exim with more. You can safely upgrade to this
238 release if you already have messages on the queue with saved ACL variable
239 values. However, if you downgrade from this release with messages on the queue,
240 any saved ACL values they may have will be lost.
242 2. The default value for rfc1413_query_timeout has been changed from 30s to 5s.
248 There was a problem with 4.52/TF/02 in that a "name=" option on control=
249 submission terminated at the next slash, thereby not allowing for slashes in
250 the name. This has been changed so that "name=" takes the rest of the string as
251 its data. It must therefore be the last option.
257 If you are using the experimental Domain Keys support, you must upgrade to
258 at least libdomainkeys 0.67 in order to run this release of Exim.
264 1. The format in which GnuTLS parameters are cached (in the file gnutls-params
265 in the spool directory) has been changed. The new format can also be generated
266 externally, so it is now possible to update the values from outside Exim. This
267 has been implemented in an upwards, BUT NOT downwards, compatible manner.
268 Upgrading should be seamless: when Exim finds that it cannot understand an
269 existing cache file, it generates new parameters and writes them to the cache
270 in the new format. If, however, you downgrade from 4.51 to a previous release,
271 you MUST delete the gnutls-params file in the spool directory, because the
272 older Exim will not recognize the new format.
274 2. When doing a callout as part of verifying an address, Exim was not paying
275 attention to any local part prefix or suffix that was matched by the router
276 that accepted the address. It now behaves in the same way as it does for
277 delivery: the affixes are removed from the local part unless
278 rcpt_include_affixes is set on the transport. If you have a configuration that
279 uses prefixes or suffixes on addresses that could be used for callouts, and you
280 want the affixes to be retained, you must make sure that rcpt_include_affixes
281 is set on the transport.
283 3. Bounce and delay warning messages no longer contain details of delivery
284 errors, except for explicit messages (e.g. generated by :fail:) and SMTP
285 responses from remote hosts.
291 The exicyclog script has been updated to use three-digit numbers in rotated log
292 files if the maximum number to keep is greater than 99. If you are already
293 keeping more than 99, there will be an incompatible change when you upgrade.
294 You will probably want to rename your old log files to the new form before
295 running the new exicyclog.
301 RFC 3848 specifies standard names for the "with" phrase in Received: header
302 lines when AUTH and/or TLS are in use. This is the "received protocol"
303 field. Exim used to use "asmtp" for authenticated SMTP, without any
304 indication (in the protocol name) for TLS use. Now it follows the RFC and
305 uses "esmtpa" if the connection is authenticated, "esmtps" if it is
306 encrypted, and "esmtpsa" if it is both encrypted and authenticated. These names
307 appear in log lines as well as in Received: header lines.
313 Change 4.31/2 gave problems to data ACLs and local_scan() functions that
314 expected to see a Received: header. I have changed to yet another scheme. The
315 Received: header is now generated after the body is received, but before the
316 ACL or local_scan() is called. After they have run, the timestamp in the
317 Received: header is updated.
319 Thus, change (a) of 4.31/2 has been reversed, but change (b) is still true,
320 which is lucky, since I decided it was a bug fix.
326 If an expansion in a condition on a "warn" statement fails because a lookup
327 defers, the "warn" statement is abandoned, and the next ACL statement is
328 processed. Previously this caused the whole ACL to be aborted.
334 Change 4.31/2 has been reversed, as it proved contentious. Recipient callout
335 verification now uses <> in the MAIL command by default, as it did before. A
336 new callout option, "use_sender", has been added to request the other
343 1. If you compile Exim to use GnuTLS, it now requires the use of release 1.0.0
344 or greater. The interface to the obsolete 0.8.x releases is no longer
345 supported. There is one externally visible change: the format for the
346 display of Distinguished Names now uses commas as a separator rather than a
347 slash. This is to comply with RFC 2253.
349 2. When a message is received, the Received: header line is now generated when
350 reception is complete, instead of at the start of reception. For messages
351 that take a long time to come in, this changes the meaning of the timestamp.
352 There are several side-effects of this change:
354 (a) If a message is rejected by a DATA or non-SMTP ACL, or by local_scan(),
355 the logged header lines no longer include the local Received: line,
356 because it has not yet been created. If the message is a non-SMTP one,
357 and the error is processed by sending a message to the sender, the copy
358 of the original message that is returned does not have an added
361 (b) When a filter file is tested using -bf, no additional Received: header
362 is added to the test message. After some thought, I decided that this
365 The contents of $received_for are not affected by this change. This
366 variable still contains the single recipient of a message, copied after
367 addresses have been rewritten, but before local_scan() is run.
369 2. Recipient callout verification, like sender verification, was using <> in
370 the MAIL FROM command. This isn't really the right thing, since the actual
371 sender may affect whether the remote host accepts the recipient or not. I
372 have changed it to use the actual sender in the callout; this means that
373 the cache record is now keyed on a recipient/sender pair, not just the
374 recipient address. There doesn't seem to be a real danger of callout loops,
375 since a callout by the remote host to check the sender would use <>.
381 1. I have abolished timeout_DNS as an error that can be detected in retry
382 rules, because it has never worked. Despite the fact that it has been
383 documented since at least release 1.62, there was no code to support it.
384 If you have used it in your retry rules, you will now get a warning message
385 to the log and panic log. It is now treated as plain "timeout".
387 2. After discussion on the mailing list, Exim no longer adds From:, Date:, or
388 Message-Id: header lines to messages that do not originate locally, that is,
389 messages that have an associated sending host address.
391 3. When looking up a host name from an IP address, Exim now tries the DNS
392 first, and only if that fails does it use gethostbyaddr() (or equivalent).
393 This change was made because on some OS, not all the names are given for
394 addresses with multiple PTR records via the gethostbyaddr() interface. The
395 order of lookup can be changed by setting host_lookup_order.
401 1. The new FIXED_NEVER_USERS build-time option creates a list of "never users"
402 that cannot be overridden. The default in the distributed EDITME is "root".
403 If for some reason you were (against advice) running deliveries as root, you
404 will have to ensure that FIXED_NEVER_USERS is not set in your
407 2. The ${quote: operator now quotes an empty string, which it did not before.
409 3. Version 4.23 saves the contents of the ACL variables with the message, so
410 that they can be used later. If one of these variables contains a newline,
411 there will be a newline character in the spool that will not be interpreted
412 correctely by a previous version of Exim. (Exim ignores keyed spool file
413 items that it doesn't understand - precisely for this kind of problem - but
414 it expects them all to be on one line.)
416 So the bottom line is: if you have newlines in your ACL variables, you
417 cannot retreat from 4.23.
423 1. The idea of the "warn" ACL verb is that it adds a header or writes to the
424 log only when "message" or "log_message" are set. However, if one of the
425 conditions was an address verification, or a call to a nested ACL, the
426 messages generated by the underlying test were being passed through. This
427 no longer happens. The underlying message is available in $acl_verify_
428 message for both "message" and "log_message" expansions, so it can be
429 passed through if needed.
431 2. The way that the $h_ (and $header_) expansions work has been changed by the
432 addition of RFC 2047 decoding. See the main documentation (the NewStuff file
433 until release 4.30, then the manual) for full details. Briefly, there are
436 $rh_xxx: and $rheader_xxx: give the original content of the header
437 line(s), with no processing at all.
439 $bh_xxx: and $bheader_xxx: remove leading and trailing white space, and
440 then decode base64 or quoted-printable "words" within the header text,
441 but do not do charset translation.
443 $h_xxx: and $header_xxx: attempt to translate the $bh_ string to a
444 standard character set.
446 If you have previously been using $h_ expansions to access the raw
447 characters, you should change to $rh_ instead.
449 3. When Exim creates an RFC 2047 encoded word in a header line, it labels it
450 with the default character set from the headers_charset option instead of
451 always using iso-8859-1.
453 4. If TMPDIR is defined in Local/Makefile (default in src/EDITME is
454 TMPDIR="/tmp"), Exim checks for the presence of an environment variable
455 called TMPDIR, and if it finds it is different, it changes its value.
457 5. Following a discussion on the list, the rules by which Exim recognises line
458 endings on incoming messages have been changed. The -dropcr and drop_cr
459 options are now no-ops, retained only for backwards compatibility. The
460 following line terminators are recognized: LF CRLF CR. However, special
461 processing applies to CR:
463 (i) The sequence CR . CR does *not* terminate an incoming SMTP message,
464 nor a local message in the state where . is a terminator.
466 (ii) If a bare CR is encountered in a header line, an extra space is added
467 after the line terminator so as not to end the header. The reasoning
468 behind this is that bare CRs in header lines are most likely either
469 to be mistakes, or people trying to play silly games.
471 6. The code for using daemon_smtp_port, local_interfaces, and the -oX options
472 has been reorganized. It is supposed to be backwards compatible, but it is
473 mentioned here just in case I've screwed up.
480 1. I have tidied and re-organized the code that uses alarm() for imposing time
481 limits on various things. It shouldn't affect anything, but if you notice
482 processes getting stuck, it may be that I've broken something.
484 2. The "arguments" log selector now also logs the current working directory
487 3. An incompatible change has been made to the appendfile transport. This
488 affects the case when it is used for file deliveries that are set up by
489 .forward and filter files. Previously, any settings of the "file" or
490 "directory" options were ignored. It is hoped that, like the address_file
491 transport in the default configuration, these options were never in fact set
492 on such transports, because they were of no use.
494 Now, if either of these options is set, it is used. The path that is passed
495 by the router is in $address_file (this is not new), so it can be used as
496 part of a longer path, or modified in any other way that expansion permits.
498 If neither "file" nor "directory" is set, the behaviour is unchanged.
500 4. Related to the above: in a filter, if a "save" command specifies a non-
501 absolute path, the value of $home/ is pre-pended. This no longer happens if
502 $home is unset or is set to an empty string.
504 5. Multiple file deliveries from a filter or .forward file can never be
505 batched; the value of batch_max on the transport is ignored for file
506 deliveries. I'm assuming that nobody ever actually set batch_max on the
507 address_file transport - it would have had odd effects previously.
509 6. DESTDIR is the more common variable that ROOT for use when installing
510 software under a different root filing system. The Exim install script now
511 recognizes DESTDIR first; if it is not set, ROOT is used.
513 7. If DESTDIR is set when installing Exim, it no longer prepends its value to
514 the path of the system aliases file that appears in the default
515 configuration (when a default configuration is installed). If an aliases
516 file is actually created, its name *does* use the prefix.
522 1. The default for the maximum number of unknown SMTP commands that Exim will
523 accept before dropping a connection has been reduced from 5 to 3. However, you
524 can now change the value by setting smtp_max_unknown_commands.
526 2. The ${quote: operator has been changed so that it turns newline and carriage
527 return characters into \n and \r, respectively.
529 3. The file names used for maildir messages now include the microsecond time
530 fraction as well as the time in seconds, to cope with systems where the process
531 id can be re-used within the same second. The format is now
533 <time>.H<microsec>P<pid>.<host>
535 This should be a compatible change, but is noted here just in case.
537 4. The rules for creating message ids have changed, to cope with systems where
538 the process id can be re-used within the same second. The format, however, is
539 unchanged, so this should not cause any problems, except as noted in the next
542 5. The maximum value for localhost_number has been reduced from 255 to 16, in
543 order to implement the new message id rules. For operating systems that have
544 case-insensitive file systems (Cygwin and Darwin), the limit is 10.
546 6. verify = header_syntax was allowing unqualified addresses in all cases. Now
547 it allows them only for locally generated messages and from hosts that match
548 sender_unqualified_hosts or recipient_unqualified_hosts, respectively.
550 7. For reasons lost in the mists of time, when a pipe transport was run, the
551 environment variable MESSAGE_ID was set to the message ID preceded by 'E' (the
552 form used in Message-ID: header lines). The 'E' has been removed.
558 1. The handling of lines in the configuration file has changed. Previously,
559 macro expansion was applied to logical lines, after continuations had been
560 joined on. This meant that it could not be used in .include lines, which are
561 handled as physical rather than logical lines. Macro expansion is now done on
562 physical lines rather than logical lines. This means there are two
565 (a) A macro that expands to # to turn a line into a comment now applies only
566 to the physical line where it appears. Previously, it would have caused
567 any following continuations also to be ignored.
569 (b) A macro name can no longer be split over the boundary between a line and
570 its continuation. Actually, this is more of a bug fix. :-)
572 2. The -D command line option must now all be within one command line item.
573 This makes it possible to use -D to set a macro to the empty string by commands
579 Previously, these items would have moved on to the next item on the command
580 line. To include spaces in a macro definition item, quotes must be used, in
581 which case you can also have spaces after -D and surrounding the equals. For
584 exim '-D ABC = something' ...
586 3. The way that addresses that redirect to themselves are handled has been
587 changed, in order to fix an obscure bug. This should not cause any problems
588 except in the case of wanting to go back from a 4.11 (or later) release to an
589 earlier release. If there are undelivered messages on the spool that contain
590 addresses which redirect to themselves, and the redirected addresses have
591 already been delivered, you might get a duplicate delivery if you revert to an
594 4. The default way of looking up IP addresses for hosts in the manualroute and
595 queryprogram routers has been changed. If "byname" or "bydns" is explicitly
596 specified, there is no change, but if no method is specified, Exim now behaves
599 First, a DNS lookup is done. If this yields anything other than
600 HOST_NOT_FOUND, that result is used. Otherwise, Exim goes on to try a call to
601 getipnodebyname() (or gethostbyname() on older systems) and the result of the
602 lookup is the result of that call.
604 This change has been made because it has been discovered that on some systems,
605 if a DNS lookup called via getipnodebyname() times out, HOST_NOT_FOUND is
606 returned instead of TRY_AGAIN. Thus, it is safest to try a DNS lookup directly
607 first, and only if that gives a definite "no such host" to try the local
610 5. In fixing the minor security problem with pid_file_path, I have removed some
611 backwards-compatible (undocumented) code which was present to ease conversion
612 from Exim 3. In Exim 4, pid_file_path is a literal; in Exim 3 it was allowed to
613 contain "%s", which was replaced by the port number for daemons listening on
614 non-standard ports. In Exim 4, such daemons do not write a pid file. The
615 backwards compatibility feature was to replace "%s" by nothing if it occurred
616 in an Exim 4 setting of pid_file_path. The bug was in this code. I have solved
617 the problem by removing the backwards compatibility feature. Thus, if you still
618 have "%s" somewhere in a setting of pid_file_path, you should remove it.
620 6. There has been an extension to lsearch files. The keys in these files may
621 now be quoted in order to allow for whitespace and colons in them. This means
622 that if you were previously using keys that began with a doublequote, you will
623 now have to wrap them with extra quotes and escape the internal quotes. The
624 possibility that anybody is actually doing this seems extremely remote, but it
625 is documented just in case.
631 The build-time parameter EXIWHAT_KILL_ARG has been renamed EXIWHAT_KILL_SIGNAL
632 to better reflect its function. The OS-specific files have been updated. Only
633 if you have explicitly set this in your Makefile (highly unlikely) do you need
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