Check return values of setgid/setuid.
[exim.git] / src / README.UPDATING
2eda48c6 1$Cambridge: exim/src/README.UPDATING,v 1.17 2009/10/16 07:35:42 tom Exp $
3This document contains detailed information about incompatibilities that might
4be encountered when upgrading from one release of Exim to another. The
5information is in reverse order of release numbers. Mostly these are relatively
6small points, and the configuration file is normally upwards compatible, but
7there have been two big upheavals...
11* There was a big reworking of the way mail routing works for release *
12* 4.00. Previously used "directors" were abolished, and all routing is *
13* now done by routers. Policy controls for incoming mail are now done by *
14* Access Control Lists instead of separate options. All this means that *
15* pre-4.00 configuration files have to be massively converted. If you *
16* are coming from a 3.xx release, please read the document in the file *
17* doc/Exim4.upgrade, and allow some time to complete the upgrade. *
18* *
19* There was a big reworking of the way domain/host/net/address lists are *
20* handled at release 3.00. If you are coming from a pre-3.00 release, it *
21* might be easier to start again from a default configuration. Otherwise *
22* you need to read doc/Exim3.upgrade and do a double conversion of your *
23* configuration file. *
27The rest of this document contains information about changes in 4.xx releases
28that might affect a running system.
30Exim version 4.70
331. Experimental Yahoo! Domainkeys support has been dropped in this release.
34It has been superceded by a native implementation of its successor DKIM.
362. Up to version 4.69, Exim came with an embedded version of the PCRE library.
37As of 4.70, this is no longer the case. To compile Exim, you will need PCRE
38installed. Most OS distributions have ready-made library and develoment
42Exim version 4.68
451. The internal implementation of the database keys that are used for ACL
46ratelimiting has been tidied up. This means that an update to 4.68 might cause
47Exim to "forget" previous rates that it had calculated, and reset them to zero.
50Exim version 4.64
531. Callouts were setting the name used for EHLO/HELO from $smtp_active_
54hostname. This is wrong, because it relates to the incoming message (and
55probably the interface on which it is arriving) and not to the outgoing
56callout (which could be using a different interface). This has been
57changed to use the value of the helo_data option from the smtp transport
58instead - this is what is used when a message is actually being sent. If
59there is no remote transport (possible with a router that sets up host
60addresses), $smtp_active_hostname is used. This change is mentioned here in
61case somebody is relying on the use of $smtp_active_hostname.
632. A bug has been fixed that might just possibly be something that is relied on
64in some configurations. In expansion items such as ${if >{xxx}{yyy}...} an
65empty string (that is {}) was being interpreted as if it was {0} and therefore
66treated as the number zero. From release 4.64, such strings cause an error
67because a decimal number, possibly followed by K or M, is required (as has
68always been documented).
703. There has been a change to the GnuTLS support (ChangeLog/PH/20) to improve
71Exim's performance. Unfortunately, this has the side effect of being slightly
72non-upwards compatible for versions 4.50 and earlier. If you are upgrading from
73one of these earlier versions and you use GnuTLS, you must remove the file
74called gnutls-params in Exim's spool directory. If you don't do this, you will
75see this error:
77 TLS error on connection from ... (DH params import): Base64 decoding error.
79Removing the file causes Exim to recompute the relevant encryption parameters
80and cache them in the new format that was introduced for release 4.51 (May
812005). If you are upgrading from release 4.51 or later, there should be no
26da7e20 84
85Exim version 4.63
88When an SMTP error message is specified in a "message" modifier in an ACL, or
89in a :fail: or :defer: message in a redirect router, Exim now checks the start
90of the message for an SMTP error code. This consists of three digits followed
91by a space, optionally followed by an extended code of the form n.n.n, also
92followed by a space. If this is the case and the very first digit is the same
93as the default error code, the code from the message is used instead. If the
94very first digit is incorrect, a panic error is logged, and the default code is
95used. This is an incompatible change, but it is not expected to affect many (if
96any) configurations. It is possible to suppress the use of the supplied code in
97a redirect router by setting the smtp_error_code option false. In this case,
98any SMTP code is quietly ignored.
101Exim version 4.61
1041. The default number of ACL variables of each type has been increased to 20,
105and it's possible to compile Exim with more. You can safely upgrade to this
106release if you already have messages on the queue with saved ACL variable
107values. However, if you downgrade from this release with messages on the queue,
108any saved ACL values they may have will be lost.
1102. The default value for rfc1413_query_timeout has been changed from 30s to 5s.
113Exim version 4.54
116There was a problem with 4.52/TF/02 in that a "name=" option on control=
117submission terminated at the next slash, thereby not allowing for slashes in
118the name. This has been changed so that "name=" takes the rest of the string as
119its data. It must therefore be the last option.
122Version 4.53
125If you are using the experimental Domain Keys support, you must upgrade to
126at least libdomainkeys 0.67 in order to run this release of Exim.
129Version 4.51
1321. The format in which GnuTLS parameters are cached (in the file gnutls-params
133in the spool directory) has been changed. The new format can also be generated
134externally, so it is now possible to update the values from outside Exim. This
135has been implemented in an upwards, BUT NOT downwards, compatible manner.
136Upgrading should be seamless: when Exim finds that it cannot understand an
137existing cache file, it generates new parameters and writes them to the cache
138in the new format. If, however, you downgrade from 4.51 to a previous release,
139you MUST delete the gnutls-params file in the spool directory, because the
140older Exim will not recognize the new format.
1422. When doing a callout as part of verifying an address, Exim was not paying
143attention to any local part prefix or suffix that was matched by the router
144that accepted the address. It now behaves in the same way as it does for
145delivery: the affixes are removed from the local part unless
146rcpt_include_affixes is set on the transport. If you have a configuration that
147uses prefixes or suffixes on addresses that could be used for callouts, and you
148want the affixes to be retained, you must make sure that rcpt_include_affixes
149is set on the transport.
1513. Bounce and delay warning messages no longer contain details of delivery
152errors, except for explicit messages (e.g. generated by :fail:) and SMTP
153responses from remote hosts.
b5aea5e1 155
156Version 4.50
159The exicyclog script has been updated to use three-digit numbers in rotated log
160files if the maximum number to keep is greater than 99. If you are already
161keeping more than 99, there will be an incompatible change when you upgrade.
162You will probably want to rename your old log files to the new form before
c3af992c 163running the new exicyclog.
166Version 4.42
169RFC 3848 specifies standard names for the "with" phrase in Received: header
170lines when AUTH and/or TLS are in use. This is the "received protocol"
171field. Exim used to use "asmtp" for authenticated SMTP, without any
172indication (in the protocol name) for TLS use. Now it follows the RFC and
173uses "esmtpa" if the connection is authenticated, "esmtps" if it is
174encrypted, and "esmtpsa" if it is both encrypted and authenticated. These names
175appear in log lines as well as in Received: header lines.
178Version 4.34
181Change 4.31/2 gave problems to data ACLs and local_scan() functions that
182expected to see a Received: header. I have changed to yet another scheme. The
183Received: header is now generated after the body is received, but before the
184ACL or local_scan() is called. After they have run, the timestamp in the
185Received: header is updated.
187Thus, change (a) of 4.31/2 has been reversed, but change (b) is still true,
188which is lucky, since I decided it was a bug fix.
191Version 4.33
194If an expansion in a condition on a "warn" statement fails because a lookup
195defers, the "warn" statement is abandoned, and the next ACL statement is
196processed. Previously this caused the whole ACL to be aborted.
199Version 4.32
202Change 4.31/2 has been reversed, as it proved contentious. Recipient callout
203verification now uses <> in the MAIL command by default, as it did before. A
204new callout option, "use_sender", has been added to request the other
208Version 4.31
2111. If you compile Exim to use GnuTLS, it now requires the use of release 1.0.0
212 or greater. The interface to the obsolete 0.8.x releases is no longer
213 supported. There is one externally visible change: the format for the
214 display of Distinguished Names now uses commas as a separator rather than a
215 slash. This is to comply with RFC 2253.
2172. When a message is received, the Received: header line is now generated when
218 reception is complete, instead of at the start of reception. For messages
219 that take a long time to come in, this changes the meaning of the timestamp.
220 There are several side-effects of this change:
222 (a) If a message is rejected by a DATA or non-SMTP ACL, or by local_scan(),
223 the logged header lines no longer include the local Received: line,
224 because it has not yet been created. If the message is a non-SMTP one,
225 and the error is processed by sending a message to the sender, the copy
226 of the original message that is returned does not have an added
227 Received: line.
229 (b) When a filter file is tested using -bf, no additional Received: header
230 is added to the test message. After some thought, I decided that this
231 is a bug fix.
233 The contents of $received_for are not affected by this change. This
234 variable still contains the single recipient of a message, copied after
235 addresses have been rewritten, but before local_scan() is run.
2372. Recipient callout verification, like sender verification, was using <> in
238 the MAIL FROM command. This isn't really the right thing, since the actual
239 sender may affect whether the remote host accepts the recipient or not. I
240 have changed it to use the actual sender in the callout; this means that
241 the cache record is now keyed on a recipient/sender pair, not just the
242 recipient address. There doesn't seem to be a real danger of callout loops,
243 since a callout by the remote host to check the sender would use <>.
246Version 4.30
2491. I have abolished timeout_DNS as an error that can be detected in retry
250 rules, because it has never worked. Despite the fact that it has been
251 documented since at least release 1.62, there was no code to support it.
252 If you have used it in your retry rules, you will now get a warning message
253 to the log and panic log. It is now treated as plain "timeout".
2552. After discussion on the mailing list, Exim no longer adds From:, Date:, or
256 Message-Id: header lines to messages that do not originate locally, that is,
257 messages that have an associated sending host address.
2593. When looking up a host name from an IP address, Exim now tries the DNS
260 first, and only if that fails does it use gethostbyaddr() (or equivalent).
261 This change was made because on some OS, not all the names are given for
262 addresses with multiple PTR records via the gethostbyaddr() interface. The
263 order of lookup can be changed by setting host_lookup_order.
266Version 4.23
2691. The new FIXED_NEVER_USERS build-time option creates a list of "never users"
270 that cannot be overridden. The default in the distributed EDITME is "root".
271 If for some reason you were (against advice) running deliveries as root, you
272 will have to ensure that FIXED_NEVER_USERS is not set in your
273 Local/Makefile.
2752. The ${quote: operator now quotes an empty string, which it did not before.
2773. Version 4.23 saves the contents of the ACL variables with the message, so
278 that they can be used later. If one of these variables contains a newline,
279 there will be a newline character in the spool that will not be interpreted
280 correctely by a previous version of Exim. (Exim ignores keyed spool file
281 items that it doesn't understand - precisely for this kind of problem - but
282 it expects them all to be on one line.)
284 So the bottom line is: if you have newlines in your ACL variables, you
285 cannot retreat from 4.23.
288Version 4.21
2911. The idea of the "warn" ACL verb is that it adds a header or writes to the
292 log only when "message" or "log_message" are set. However, if one of the
293 conditions was an address verification, or a call to a nested ACL, the
294 messages generated by the underlying test were being passed through. This
295 no longer happens. The underlying message is available in $acl_verify_
296 message for both "message" and "log_message" expansions, so it can be
297 passed through if needed.
2992. The way that the $h_ (and $header_) expansions work has been changed by the
300 addition of RFC 2047 decoding. See the main documentation (the NewStuff file
301 until release 4.30, then the manual) for full details. Briefly, there are
302 now three forms:
304 $rh_xxx: and $rheader_xxx: give the original content of the header
305 line(s), with no processing at all.
307 $bh_xxx: and $bheader_xxx: remove leading and trailing white space, and
308 then decode base64 or quoted-printable "words" within the header text,
309 but do not do charset translation.
311 $h_xxx: and $header_xxx: attempt to translate the $bh_ string to a
312 standard character set.
314 If you have previously been using $h_ expansions to access the raw
315 characters, you should change to $rh_ instead.
3173. When Exim creates an RFC 2047 encoded word in a header line, it labels it
318 with the default character set from the headers_charset option instead of
319 always using iso-8859-1.
3214. If TMPDIR is defined in Local/Makefile (default in src/EDITME is
322 TMPDIR="/tmp"), Exim checks for the presence of an environment variable
323 called TMPDIR, and if it finds it is different, it changes its value.
3255. Following a discussion on the list, the rules by which Exim recognises line
326 endings on incoming messages have been changed. The -dropcr and drop_cr
327 options are now no-ops, retained only for backwards compatibility. The
328 following line terminators are recognized: LF CRLF CR. However, special
329 processing applies to CR:
331 (i) The sequence CR . CR does *not* terminate an incoming SMTP message,
332 nor a local message in the state where . is a terminator.
334 (ii) If a bare CR is encountered in a header line, an extra space is added
335 after the line terminator so as not to end the header. The reasoning
336 behind this is that bare CRs in header lines are most likely either
337 to be mistakes, or people trying to play silly games.
3396. The code for using daemon_smtp_port, local_interfaces, and the -oX options
340 has been reorganized. It is supposed to be backwards compatible, but it is
341 mentioned here just in case I've screwed up.
345Version 4.20
3481. I have tidied and re-organized the code that uses alarm() for imposing time
349 limits on various things. It shouldn't affect anything, but if you notice
350 processes getting stuck, it may be that I've broken something.
3522. The "arguments" log selector now also logs the current working directory
353 when Exim is called.
3553. An incompatible change has been made to the appendfile transport. This
356 affects the case when it is used for file deliveries that are set up by
357 .forward and filter files. Previously, any settings of the "file" or
358 "directory" options were ignored. It is hoped that, like the address_file
359 transport in the default configuration, these options were never in fact set
360 on such transports, because they were of no use.
362 Now, if either of these options is set, it is used. The path that is passed
363 by the router is in $address_file (this is not new), so it can be used as
364 part of a longer path, or modified in any other way that expansion permits.
366 If neither "file" nor "directory" is set, the behaviour is unchanged.
3684. Related to the above: in a filter, if a "save" command specifies a non-
369 absolute path, the value of $home/ is pre-pended. This no longer happens if
370 $home is unset or is set to an empty string.
3725. Multiple file deliveries from a filter or .forward file can never be
373 batched; the value of batch_max on the transport is ignored for file
374 deliveries. I'm assuming that nobody ever actually set batch_max on the
375 address_file transport - it would have had odd effects previously.
3776. DESTDIR is the more common variable that ROOT for use when installing
378 software under a different root filing system. The Exim install script now
379 recognizes DESTDIR first; if it is not set, ROOT is used.
3817. If DESTDIR is set when installing Exim, it no longer prepends its value to
382 the path of the system aliases file that appears in the default
383 configuration (when a default configuration is installed). If an aliases
384 file is actually created, its name *does* use the prefix.
387Version 4.14
3901. The default for the maximum number of unknown SMTP commands that Exim will
391accept before dropping a connection has been reduced from 5 to 3. However, you
392can now change the value by setting smtp_max_unknown_commands.
3942. The ${quote: operator has been changed so that it turns newline and carriage
395return characters into \n and \r, respectively.
3973. The file names used for maildir messages now include the microsecond time
398fraction as well as the time in seconds, to cope with systems where the process
399id can be re-used within the same second. The format is now
401 <time>.H<microsec>P<pid>.<host>
403This should be a compatible change, but is noted here just in case.
4054. The rules for creating message ids have changed, to cope with systems where
406the process id can be re-used within the same second. The format, however, is
407unchanged, so this should not cause any problems, except as noted in the next
4105. The maximum value for localhost_number has been reduced from 255 to 16, in
411order to implement the new message id rules. For operating systems that have
412case-insensitive file systems (Cygwin and Darwin), the limit is 10.
4146. verify = header_syntax was allowing unqualified addresses in all cases. Now
415it allows them only for locally generated messages and from hosts that match
416sender_unqualified_hosts or recipient_unqualified_hosts, respectively.
4187. For reasons lost in the mists of time, when a pipe transport was run, the
419environment variable MESSAGE_ID was set to the message ID preceded by 'E' (the
420form used in Message-ID: header lines). The 'E' has been removed.
423Version 4.11
4261. The handling of lines in the configuration file has changed. Previously,
427macro expansion was applied to logical lines, after continuations had been
428joined on. This meant that it could not be used in .include lines, which are
429handled as physical rather than logical lines. Macro expansion is now done on
430physical lines rather than logical lines. This means there are two
433 (a) A macro that expands to # to turn a line into a comment now applies only
434 to the physical line where it appears. Previously, it would have caused
435 any following continuations also to be ignored.
437 (b) A macro name can no longer be split over the boundary between a line and
438 its continuation. Actually, this is more of a bug fix. :-)
4402. The -D command line option must now all be within one command line item.
441This makes it possible to use -D to set a macro to the empty string by commands
442such as
444 exim -DABC ...
445 exim -DABC= ...
447Previously, these items would have moved on to the next item on the command
448line. To include spaces in a macro definition item, quotes must be used, in
449which case you can also have spaces after -D and surrounding the equals. For
452 exim '-D ABC = something' ...
4543. The way that addresses that redirect to themselves are handled has been
455changed, in order to fix an obscure bug. This should not cause any problems
456except in the case of wanting to go back from a 4.11 (or later) release to an
457earlier release. If there are undelivered messages on the spool that contain
458addresses which redirect to themselves, and the redirected addresses have
459already been delivered, you might get a duplicate delivery if you revert to an
460earlier Exim.
4624. The default way of looking up IP addresses for hosts in the manualroute and
463queryprogram routers has been changed. If "byname" or "bydns" is explicitly
464specified, there is no change, but if no method is specified, Exim now behaves
465as follows:
467 First, a DNS lookup is done. If this yields anything other than
468 HOST_NOT_FOUND, that result is used. Otherwise, Exim goes on to try a call to
469 getipnodebyname() (or gethostbyname() on older systems) and the result of the
470 lookup is the result of that call.
472This change has been made because it has been discovered that on some systems,
473if a DNS lookup called via getipnodebyname() times out, HOST_NOT_FOUND is
474returned instead of TRY_AGAIN. Thus, it is safest to try a DNS lookup directly
475first, and only if that gives a definite "no such host" to try the local
4785. In fixing the minor security problem with pid_file_path, I have removed some
479backwards-compatible (undocumented) code which was present to ease conversion
480from Exim 3. In Exim 4, pid_file_path is a literal; in Exim 3 it was allowed to
481contain "%s", which was replaced by the port number for daemons listening on
482non-standard ports. In Exim 4, such daemons do not write a pid file. The
483backwards compatibility feature was to replace "%s" by nothing if it occurred
484in an Exim 4 setting of pid_file_path. The bug was in this code. I have solved
485the problem by removing the backwards compatibility feature. Thus, if you still
486have "%s" somewhere in a setting of pid_file_path, you should remove it.
4886. There has been an extension to lsearch files. The keys in these files may
489now be quoted in order to allow for whitespace and colons in them. This means
490that if you were previously using keys that began with a doublequote, you will
491now have to wrap them with extra quotes and escape the internal quotes. The
492possibility that anybody is actually doing this seems extremely remote, but it
493is documented just in case.
496Version 4.10
499The build-time parameter EXIWHAT_KILL_ARG has been renamed EXIWHAT_KILL_SIGNAL
500to better reflect its function. The OS-specific files have been updated. Only
501if you have explicitly set this in your Makefile (highly unlikely) do you need
502to change anything.