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 match_<type>{string1}{string2} expansion conditions no longer subject
33 string2 to string expansion, unless Exim was built with the new
34 "EXPAND_LISTMATCH_RHS" option. Too many people have inadvertently created
35 insecure configurations that way. If you need the functionality and turn on
36 that build option, please let the developers know, and know why, so we can
37 try to provide a safer mechanism for you.
43 * The integrated support for dynamically loadable lookup modules has an ABI
44 change from the modules supported by some OS vendors through an unofficial
45 patch. Don't try to mix & match.
47 * Some parts of the build system are now beginning to assume that the host
48 environment is POSIX. If you're building on a system where POSIX tools are
49 not the default, you might have an easier time if you switch to the POSIX
50 tools. Feel free to report non-POSIX issues as a request for a feature
51 enhancement, but if the POSIX variants are available then the fix will
52 probably just involve some coercion. See the README instructions for
53 building on such hosts.
59 * The Exim run-time user can no longer be root; this was always
60 strongly discouraged, but is now prohibited both at build and
61 run-time. If you need Exim to run routinely as root, you'll need to
62 patch the source and accept the risk. Here be dragons.
64 * Exim will no longer accept a configuration file owned by the Exim
65 run-time user, unless that account is explicitly the value in
66 CONFIGURE_OWNER, which we discourage. Exim now checks to ensure that
67 files are not writable by other accounts.
69 * The ALT_CONFIG_ROOT_ONLY build option is no longer optional and is forced
70 on; the Exim user can, by default, no longer use -C/-D and retain privilege.
71 Two new build options mitigate this.
73 * TRUSTED_CONFIG_LIST defines a file containing a whitelist of config
74 files that are trusted to be selected by the Exim user; one per line.
75 This is the recommended approach going forward.
77 * WHITELIST_D_MACROS defines a colon-separated list of macro names which
78 the Exim run-time user may safely pass without dropping privileges.
79 Because changes to this involve a recompile, this is not the recommended
80 approach but may ease transition. The values of the macros, when
81 overridden, are constrained to match this regex: ^[A-Za-z0-9_/.-]*$
83 * The system_filter_user option now defaults to the Exim run-time user,
84 rather than root. You can still set it explicitly to root and this
85 can be done with prior versions too, letting you roll versions
86 without needing to change this configuration option.
88 * ClamAV must be at least version 0.95 unless WITH_OLD_CLAMAV_STREAM is
89 defined at build time.
95 1. Experimental Yahoo! Domainkeys support has been dropped in this release.
96 It has been superceded by a native implementation of its successor DKIM.
98 2. Up to version 4.69, Exim came with an embedded version of the PCRE library.
99 As of 4.70, this is no longer the case. To compile Exim, you will need PCRE
100 installed. Most OS distributions have ready-made library and develoment
107 1. The internal implementation of the database keys that are used for ACL
108 ratelimiting has been tidied up. This means that an update to 4.68 might cause
109 Exim to "forget" previous rates that it had calculated, and reset them to zero.
115 1. Callouts were setting the name used for EHLO/HELO from $smtp_active_
116 hostname. This is wrong, because it relates to the incoming message (and
117 probably the interface on which it is arriving) and not to the outgoing
118 callout (which could be using a different interface). This has been
119 changed to use the value of the helo_data option from the smtp transport
120 instead - this is what is used when a message is actually being sent. If
121 there is no remote transport (possible with a router that sets up host
122 addresses), $smtp_active_hostname is used. This change is mentioned here in
123 case somebody is relying on the use of $smtp_active_hostname.
125 2. A bug has been fixed that might just possibly be something that is relied on
126 in some configurations. In expansion items such as ${if >{xxx}{yyy}...} an
127 empty string (that is {}) was being interpreted as if it was {0} and therefore
128 treated as the number zero. From release 4.64, such strings cause an error
129 because a decimal number, possibly followed by K or M, is required (as has
130 always been documented).
132 3. There has been a change to the GnuTLS support (ChangeLog/PH/20) to improve
133 Exim's performance. Unfortunately, this has the side effect of being slightly
134 non-upwards compatible for versions 4.50 and earlier. If you are upgrading from
135 one of these earlier versions and you use GnuTLS, you must remove the file
136 called gnutls-params in Exim's spool directory. If you don't do this, you will
139 TLS error on connection from ... (DH params import): Base64 decoding error.
141 Removing the file causes Exim to recompute the relevant encryption parameters
142 and cache them in the new format that was introduced for release 4.51 (May
143 2005). If you are upgrading from release 4.51 or later, there should be no
150 When an SMTP error message is specified in a "message" modifier in an ACL, or
151 in a :fail: or :defer: message in a redirect router, Exim now checks the start
152 of the message for an SMTP error code. This consists of three digits followed
153 by a space, optionally followed by an extended code of the form n.n.n, also
154 followed by a space. If this is the case and the very first digit is the same
155 as the default error code, the code from the message is used instead. If the
156 very first digit is incorrect, a panic error is logged, and the default code is
157 used. This is an incompatible change, but it is not expected to affect many (if
158 any) configurations. It is possible to suppress the use of the supplied code in
159 a redirect router by setting the smtp_error_code option false. In this case,
160 any SMTP code is quietly ignored.
166 1. The default number of ACL variables of each type has been increased to 20,
167 and it's possible to compile Exim with more. You can safely upgrade to this
168 release if you already have messages on the queue with saved ACL variable
169 values. However, if you downgrade from this release with messages on the queue,
170 any saved ACL values they may have will be lost.
172 2. The default value for rfc1413_query_timeout has been changed from 30s to 5s.
178 There was a problem with 4.52/TF/02 in that a "name=" option on control=
179 submission terminated at the next slash, thereby not allowing for slashes in
180 the name. This has been changed so that "name=" takes the rest of the string as
181 its data. It must therefore be the last option.
187 If you are using the experimental Domain Keys support, you must upgrade to
188 at least libdomainkeys 0.67 in order to run this release of Exim.
194 1. The format in which GnuTLS parameters are cached (in the file gnutls-params
195 in the spool directory) has been changed. The new format can also be generated
196 externally, so it is now possible to update the values from outside Exim. This
197 has been implemented in an upwards, BUT NOT downwards, compatible manner.
198 Upgrading should be seamless: when Exim finds that it cannot understand an
199 existing cache file, it generates new parameters and writes them to the cache
200 in the new format. If, however, you downgrade from 4.51 to a previous release,
201 you MUST delete the gnutls-params file in the spool directory, because the
202 older Exim will not recognize the new format.
204 2. When doing a callout as part of verifying an address, Exim was not paying
205 attention to any local part prefix or suffix that was matched by the router
206 that accepted the address. It now behaves in the same way as it does for
207 delivery: the affixes are removed from the local part unless
208 rcpt_include_affixes is set on the transport. If you have a configuration that
209 uses prefixes or suffixes on addresses that could be used for callouts, and you
210 want the affixes to be retained, you must make sure that rcpt_include_affixes
211 is set on the transport.
213 3. Bounce and delay warning messages no longer contain details of delivery
214 errors, except for explicit messages (e.g. generated by :fail:) and SMTP
215 responses from remote hosts.
221 The exicyclog script has been updated to use three-digit numbers in rotated log
222 files if the maximum number to keep is greater than 99. If you are already
223 keeping more than 99, there will be an incompatible change when you upgrade.
224 You will probably want to rename your old log files to the new form before
225 running the new exicyclog.
231 RFC 3848 specifies standard names for the "with" phrase in Received: header
232 lines when AUTH and/or TLS are in use. This is the "received protocol"
233 field. Exim used to use "asmtp" for authenticated SMTP, without any
234 indication (in the protocol name) for TLS use. Now it follows the RFC and
235 uses "esmtpa" if the connection is authenticated, "esmtps" if it is
236 encrypted, and "esmtpsa" if it is both encrypted and authenticated. These names
237 appear in log lines as well as in Received: header lines.
243 Change 4.31/2 gave problems to data ACLs and local_scan() functions that
244 expected to see a Received: header. I have changed to yet another scheme. The
245 Received: header is now generated after the body is received, but before the
246 ACL or local_scan() is called. After they have run, the timestamp in the
247 Received: header is updated.
249 Thus, change (a) of 4.31/2 has been reversed, but change (b) is still true,
250 which is lucky, since I decided it was a bug fix.
256 If an expansion in a condition on a "warn" statement fails because a lookup
257 defers, the "warn" statement is abandoned, and the next ACL statement is
258 processed. Previously this caused the whole ACL to be aborted.
264 Change 4.31/2 has been reversed, as it proved contentious. Recipient callout
265 verification now uses <> in the MAIL command by default, as it did before. A
266 new callout option, "use_sender", has been added to request the other
273 1. If you compile Exim to use GnuTLS, it now requires the use of release 1.0.0
274 or greater. The interface to the obsolete 0.8.x releases is no longer
275 supported. There is one externally visible change: the format for the
276 display of Distinguished Names now uses commas as a separator rather than a
277 slash. This is to comply with RFC 2253.
279 2. When a message is received, the Received: header line is now generated when
280 reception is complete, instead of at the start of reception. For messages
281 that take a long time to come in, this changes the meaning of the timestamp.
282 There are several side-effects of this change:
284 (a) If a message is rejected by a DATA or non-SMTP ACL, or by local_scan(),
285 the logged header lines no longer include the local Received: line,
286 because it has not yet been created. If the message is a non-SMTP one,
287 and the error is processed by sending a message to the sender, the copy
288 of the original message that is returned does not have an added
291 (b) When a filter file is tested using -bf, no additional Received: header
292 is added to the test message. After some thought, I decided that this
295 The contents of $received_for are not affected by this change. This
296 variable still contains the single recipient of a message, copied after
297 addresses have been rewritten, but before local_scan() is run.
299 2. Recipient callout verification, like sender verification, was using <> in
300 the MAIL FROM command. This isn't really the right thing, since the actual
301 sender may affect whether the remote host accepts the recipient or not. I
302 have changed it to use the actual sender in the callout; this means that
303 the cache record is now keyed on a recipient/sender pair, not just the
304 recipient address. There doesn't seem to be a real danger of callout loops,
305 since a callout by the remote host to check the sender would use <>.
311 1. I have abolished timeout_DNS as an error that can be detected in retry
312 rules, because it has never worked. Despite the fact that it has been
313 documented since at least release 1.62, there was no code to support it.
314 If you have used it in your retry rules, you will now get a warning message
315 to the log and panic log. It is now treated as plain "timeout".
317 2. After discussion on the mailing list, Exim no longer adds From:, Date:, or
318 Message-Id: header lines to messages that do not originate locally, that is,
319 messages that have an associated sending host address.
321 3. When looking up a host name from an IP address, Exim now tries the DNS
322 first, and only if that fails does it use gethostbyaddr() (or equivalent).
323 This change was made because on some OS, not all the names are given for
324 addresses with multiple PTR records via the gethostbyaddr() interface. The
325 order of lookup can be changed by setting host_lookup_order.
331 1. The new FIXED_NEVER_USERS build-time option creates a list of "never users"
332 that cannot be overridden. The default in the distributed EDITME is "root".
333 If for some reason you were (against advice) running deliveries as root, you
334 will have to ensure that FIXED_NEVER_USERS is not set in your
337 2. The ${quote: operator now quotes an empty string, which it did not before.
339 3. Version 4.23 saves the contents of the ACL variables with the message, so
340 that they can be used later. If one of these variables contains a newline,
341 there will be a newline character in the spool that will not be interpreted
342 correctely by a previous version of Exim. (Exim ignores keyed spool file
343 items that it doesn't understand - precisely for this kind of problem - but
344 it expects them all to be on one line.)
346 So the bottom line is: if you have newlines in your ACL variables, you
347 cannot retreat from 4.23.
353 1. The idea of the "warn" ACL verb is that it adds a header or writes to the
354 log only when "message" or "log_message" are set. However, if one of the
355 conditions was an address verification, or a call to a nested ACL, the
356 messages generated by the underlying test were being passed through. This
357 no longer happens. The underlying message is available in $acl_verify_
358 message for both "message" and "log_message" expansions, so it can be
359 passed through if needed.
361 2. The way that the $h_ (and $header_) expansions work has been changed by the
362 addition of RFC 2047 decoding. See the main documentation (the NewStuff file
363 until release 4.30, then the manual) for full details. Briefly, there are
366 $rh_xxx: and $rheader_xxx: give the original content of the header
367 line(s), with no processing at all.
369 $bh_xxx: and $bheader_xxx: remove leading and trailing white space, and
370 then decode base64 or quoted-printable "words" within the header text,
371 but do not do charset translation.
373 $h_xxx: and $header_xxx: attempt to translate the $bh_ string to a
374 standard character set.
376 If you have previously been using $h_ expansions to access the raw
377 characters, you should change to $rh_ instead.
379 3. When Exim creates an RFC 2047 encoded word in a header line, it labels it
380 with the default character set from the headers_charset option instead of
381 always using iso-8859-1.
383 4. If TMPDIR is defined in Local/Makefile (default in src/EDITME is
384 TMPDIR="/tmp"), Exim checks for the presence of an environment variable
385 called TMPDIR, and if it finds it is different, it changes its value.
387 5. Following a discussion on the list, the rules by which Exim recognises line
388 endings on incoming messages have been changed. The -dropcr and drop_cr
389 options are now no-ops, retained only for backwards compatibility. The
390 following line terminators are recognized: LF CRLF CR. However, special
391 processing applies to CR:
393 (i) The sequence CR . CR does *not* terminate an incoming SMTP message,
394 nor a local message in the state where . is a terminator.
396 (ii) If a bare CR is encountered in a header line, an extra space is added
397 after the line terminator so as not to end the header. The reasoning
398 behind this is that bare CRs in header lines are most likely either
399 to be mistakes, or people trying to play silly games.
401 6. The code for using daemon_smtp_port, local_interfaces, and the -oX options
402 has been reorganized. It is supposed to be backwards compatible, but it is
403 mentioned here just in case I've screwed up.
410 1. I have tidied and re-organized the code that uses alarm() for imposing time
411 limits on various things. It shouldn't affect anything, but if you notice
412 processes getting stuck, it may be that I've broken something.
414 2. The "arguments" log selector now also logs the current working directory
417 3. An incompatible change has been made to the appendfile transport. This
418 affects the case when it is used for file deliveries that are set up by
419 .forward and filter files. Previously, any settings of the "file" or
420 "directory" options were ignored. It is hoped that, like the address_file
421 transport in the default configuration, these options were never in fact set
422 on such transports, because they were of no use.
424 Now, if either of these options is set, it is used. The path that is passed
425 by the router is in $address_file (this is not new), so it can be used as
426 part of a longer path, or modified in any other way that expansion permits.
428 If neither "file" nor "directory" is set, the behaviour is unchanged.
430 4. Related to the above: in a filter, if a "save" command specifies a non-
431 absolute path, the value of $home/ is pre-pended. This no longer happens if
432 $home is unset or is set to an empty string.
434 5. Multiple file deliveries from a filter or .forward file can never be
435 batched; the value of batch_max on the transport is ignored for file
436 deliveries. I'm assuming that nobody ever actually set batch_max on the
437 address_file transport - it would have had odd effects previously.
439 6. DESTDIR is the more common variable that ROOT for use when installing
440 software under a different root filing system. The Exim install script now
441 recognizes DESTDIR first; if it is not set, ROOT is used.
443 7. If DESTDIR is set when installing Exim, it no longer prepends its value to
444 the path of the system aliases file that appears in the default
445 configuration (when a default configuration is installed). If an aliases
446 file is actually created, its name *does* use the prefix.
452 1. The default for the maximum number of unknown SMTP commands that Exim will
453 accept before dropping a connection has been reduced from 5 to 3. However, you
454 can now change the value by setting smtp_max_unknown_commands.
456 2. The ${quote: operator has been changed so that it turns newline and carriage
457 return characters into \n and \r, respectively.
459 3. The file names used for maildir messages now include the microsecond time
460 fraction as well as the time in seconds, to cope with systems where the process
461 id can be re-used within the same second. The format is now
463 <time>.H<microsec>P<pid>.<host>
465 This should be a compatible change, but is noted here just in case.
467 4. The rules for creating message ids have changed, to cope with systems where
468 the process id can be re-used within the same second. The format, however, is
469 unchanged, so this should not cause any problems, except as noted in the next
472 5. The maximum value for localhost_number has been reduced from 255 to 16, in
473 order to implement the new message id rules. For operating systems that have
474 case-insensitive file systems (Cygwin and Darwin), the limit is 10.
476 6. verify = header_syntax was allowing unqualified addresses in all cases. Now
477 it allows them only for locally generated messages and from hosts that match
478 sender_unqualified_hosts or recipient_unqualified_hosts, respectively.
480 7. For reasons lost in the mists of time, when a pipe transport was run, the
481 environment variable MESSAGE_ID was set to the message ID preceded by 'E' (the
482 form used in Message-ID: header lines). The 'E' has been removed.
488 1. The handling of lines in the configuration file has changed. Previously,
489 macro expansion was applied to logical lines, after continuations had been
490 joined on. This meant that it could not be used in .include lines, which are
491 handled as physical rather than logical lines. Macro expansion is now done on
492 physical lines rather than logical lines. This means there are two
495 (a) A macro that expands to # to turn a line into a comment now applies only
496 to the physical line where it appears. Previously, it would have caused
497 any following continuations also to be ignored.
499 (b) A macro name can no longer be split over the boundary between a line and
500 its continuation. Actually, this is more of a bug fix. :-)
502 2. The -D command line option must now all be within one command line item.
503 This makes it possible to use -D to set a macro to the empty string by commands
509 Previously, these items would have moved on to the next item on the command
510 line. To include spaces in a macro definition item, quotes must be used, in
511 which case you can also have spaces after -D and surrounding the equals. For
514 exim '-D ABC = something' ...
516 3. The way that addresses that redirect to themselves are handled has been
517 changed, in order to fix an obscure bug. This should not cause any problems
518 except in the case of wanting to go back from a 4.11 (or later) release to an
519 earlier release. If there are undelivered messages on the spool that contain
520 addresses which redirect to themselves, and the redirected addresses have
521 already been delivered, you might get a duplicate delivery if you revert to an
524 4. The default way of looking up IP addresses for hosts in the manualroute and
525 queryprogram routers has been changed. If "byname" or "bydns" is explicitly
526 specified, there is no change, but if no method is specified, Exim now behaves
529 First, a DNS lookup is done. If this yields anything other than
530 HOST_NOT_FOUND, that result is used. Otherwise, Exim goes on to try a call to
531 getipnodebyname() (or gethostbyname() on older systems) and the result of the
532 lookup is the result of that call.
534 This change has been made because it has been discovered that on some systems,
535 if a DNS lookup called via getipnodebyname() times out, HOST_NOT_FOUND is
536 returned instead of TRY_AGAIN. Thus, it is safest to try a DNS lookup directly
537 first, and only if that gives a definite "no such host" to try the local
540 5. In fixing the minor security problem with pid_file_path, I have removed some
541 backwards-compatible (undocumented) code which was present to ease conversion
542 from Exim 3. In Exim 4, pid_file_path is a literal; in Exim 3 it was allowed to
543 contain "%s", which was replaced by the port number for daemons listening on
544 non-standard ports. In Exim 4, such daemons do not write a pid file. The
545 backwards compatibility feature was to replace "%s" by nothing if it occurred
546 in an Exim 4 setting of pid_file_path. The bug was in this code. I have solved
547 the problem by removing the backwards compatibility feature. Thus, if you still
548 have "%s" somewhere in a setting of pid_file_path, you should remove it.
550 6. There has been an extension to lsearch files. The keys in these files may
551 now be quoted in order to allow for whitespace and colons in them. This means
552 that if you were previously using keys that began with a doublequote, you will
553 now have to wrap them with extra quotes and escape the internal quotes. The
554 possibility that anybody is actually doing this seems extremely remote, but it
555 is documented just in case.
561 The build-time parameter EXIWHAT_KILL_ARG has been renamed EXIWHAT_KILL_SIGNAL
562 to better reflect its function. The OS-specific files have been updated. Only
563 if you have explicitly set this in your Makefile (highly unlikely) do you need
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