Note about GnuTLS incompatibility for updates from 4.50 and earlier.
[exim.git] / src / README.UPDATING
1 $Cambridge: exim/src/README.UPDATING,v 1.15 2006/10/23 09:14:50 ph10 Exp $
3 This document contains detailed information about incompatibilities that might
4 be encountered when upgrading from one release of Exim to another. The
5 information is in reverse order of release numbers. Mostly these are relatively
6 small points, and the configuration file is normally upwards compatible, but
7 there have been two big upheavals...
10 **************************************************************************
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. *
24 **************************************************************************
27 The rest of this document contains information about changes in 4.xx releases
28 that might affect a running system.
31 Exim version 4.64
32 -----------------
34 1. Callouts were setting the name used for EHLO/HELO from $smtp_active_
35 hostname. This is wrong, because it relates to the incoming message (and
36 probably the interface on which it is arriving) and not to the outgoing
37 callout (which could be using a different interface). This has been
38 changed to use the value of the helo_data option from the smtp transport
39 instead - this is what is used when a message is actually being sent. If
40 there is no remote transport (possible with a router that sets up host
41 addresses), $smtp_active_hostname is used. This change is mentioned here in
42 case somebody is relying on the use of $smtp_active_hostname.
44 2. A bug has been fixed that might just possibly be something that is relied on
45 in some configurations. In expansion items such as ${if >{xxx}{yyy}...} an
46 empty string (that is {}) was being interpreted as if it was {0} and therefore
47 treated as the number zero. From release 4.64, such strings cause an error
48 because a decimal number, possibly followed by K or M, is required (as has
49 always been documented).
51 3. There has been a change to the GnuTLS support (ChangeLog/PH/20) to improve
52 Exim's performance. Unfortunately, this has the side effect of being slightly
53 non-upwards compatible for versions 4.50 and earlier. If you are upgrading from
54 one of these earlier versions and you use GnuTLS, you must remove the file
55 called gnutls-params in Exim's spool directory. If you don't do this, you will
56 see this error:
58 TLS error on connection from ... (DH params import): Base64 decoding error.
60 Removing the file causes Exim to recompute the relevant encryption parameters
61 and cache them in the new format that was introduced for release 4.51 (May
62 2005). If you are upgrading from release 4.51 or later, there should be no
63 problem.
66 Exim version 4.63
67 -----------------
69 When an SMTP error message is specified in a "message" modifier in an ACL, or
70 in a :fail: or :defer: message in a redirect router, Exim now checks the start
71 of the message for an SMTP error code. This consists of three digits followed
72 by a space, optionally followed by an extended code of the form n.n.n, also
73 followed by a space. If this is the case and the very first digit is the same
74 as the default error code, the code from the message is used instead. If the
75 very first digit is incorrect, a panic error is logged, and the default code is
76 used. This is an incompatible change, but it is not expected to affect many (if
77 any) configurations. It is possible to suppress the use of the supplied code in
78 a redirect router by setting the smtp_error_code option false. In this case,
79 any SMTP code is quietly ignored.
82 Exim version 4.61
83 -----------------
85 1. The default number of ACL variables of each type has been increased to 20,
86 and it's possible to compile Exim with more. You can safely upgrade to this
87 release if you already have messages on the queue with saved ACL variable
88 values. However, if you downgrade from this release with messages on the queue,
89 any saved ACL values they may have will be lost.
91 2. The default value for rfc1413_query_timeout has been changed from 30s to 5s.
94 Exim version 4.54
95 -----------------
97 There was a problem with 4.52/TF/02 in that a "name=" option on control=
98 submission terminated at the next slash, thereby not allowing for slashes in
99 the name. This has been changed so that "name=" takes the rest of the string as
100 its data. It must therefore be the last option.
103 Version 4.53
104 ------------
106 If you are using the experimental Domain Keys support, you must upgrade to
107 at least libdomainkeys 0.67 in order to run this release of Exim.
110 Version 4.51
111 ------------
113 1. The format in which GnuTLS parameters are cached (in the file gnutls-params
114 in the spool directory) has been changed. The new format can also be generated
115 externally, so it is now possible to update the values from outside Exim. This
116 has been implemented in an upwards, BUT NOT downwards, compatible manner.
117 Upgrading should be seamless: when Exim finds that it cannot understand an
118 existing cache file, it generates new parameters and writes them to the cache
119 in the new format. If, however, you downgrade from 4.51 to a previous release,
120 you MUST delete the gnutls-params file in the spool directory, because the
121 older Exim will not recognize the new format.
123 2. When doing a callout as part of verifying an address, Exim was not paying
124 attention to any local part prefix or suffix that was matched by the router
125 that accepted the address. It now behaves in the same way as it does for
126 delivery: the affixes are removed from the local part unless
127 rcpt_include_affixes is set on the transport. If you have a configuration that
128 uses prefixes or suffixes on addresses that could be used for callouts, and you
129 want the affixes to be retained, you must make sure that rcpt_include_affixes
130 is set on the transport.
132 3. Bounce and delay warning messages no longer contain details of delivery
133 errors, except for explicit messages (e.g. generated by :fail:) and SMTP
134 responses from remote hosts.
137 Version 4.50
138 ------------
140 The exicyclog script has been updated to use three-digit numbers in rotated log
141 files if the maximum number to keep is greater than 99. If you are already
142 keeping more than 99, there will be an incompatible change when you upgrade.
143 You will probably want to rename your old log files to the new form before
144 running the new exicyclog.
147 Version 4.42
148 ------------
150 RFC 3848 specifies standard names for the "with" phrase in Received: header
151 lines when AUTH and/or TLS are in use. This is the "received protocol"
152 field. Exim used to use "asmtp" for authenticated SMTP, without any
153 indication (in the protocol name) for TLS use. Now it follows the RFC and
154 uses "esmtpa" if the connection is authenticated, "esmtps" if it is
155 encrypted, and "esmtpsa" if it is both encrypted and authenticated. These names
156 appear in log lines as well as in Received: header lines.
159 Version 4.34
160 ------------
162 Change 4.31/2 gave problems to data ACLs and local_scan() functions that
163 expected to see a Received: header. I have changed to yet another scheme. The
164 Received: header is now generated after the body is received, but before the
165 ACL or local_scan() is called. After they have run, the timestamp in the
166 Received: header is updated.
168 Thus, change (a) of 4.31/2 has been reversed, but change (b) is still true,
169 which is lucky, since I decided it was a bug fix.
172 Version 4.33
173 ------------
175 If an expansion in a condition on a "warn" statement fails because a lookup
176 defers, the "warn" statement is abandoned, and the next ACL statement is
177 processed. Previously this caused the whole ACL to be aborted.
180 Version 4.32
181 ------------
183 Change 4.31/2 has been reversed, as it proved contentious. Recipient callout
184 verification now uses <> in the MAIL command by default, as it did before. A
185 new callout option, "use_sender", has been added to request the other
186 behaviour.
189 Version 4.31
190 ------------
192 1. If you compile Exim to use GnuTLS, it now requires the use of release 1.0.0
193 or greater. The interface to the obsolete 0.8.x releases is no longer
194 supported. There is one externally visible change: the format for the
195 display of Distinguished Names now uses commas as a separator rather than a
196 slash. This is to comply with RFC 2253.
198 2. When a message is received, the Received: header line is now generated when
199 reception is complete, instead of at the start of reception. For messages
200 that take a long time to come in, this changes the meaning of the timestamp.
201 There are several side-effects of this change:
203 (a) If a message is rejected by a DATA or non-SMTP ACL, or by local_scan(),
204 the logged header lines no longer include the local Received: line,
205 because it has not yet been created. If the message is a non-SMTP one,
206 and the error is processed by sending a message to the sender, the copy
207 of the original message that is returned does not have an added
208 Received: line.
210 (b) When a filter file is tested using -bf, no additional Received: header
211 is added to the test message. After some thought, I decided that this
212 is a bug fix.
214 The contents of $received_for are not affected by this change. This
215 variable still contains the single recipient of a message, copied after
216 addresses have been rewritten, but before local_scan() is run.
218 2. Recipient callout verification, like sender verification, was using <> in
219 the MAIL FROM command. This isn't really the right thing, since the actual
220 sender may affect whether the remote host accepts the recipient or not. I
221 have changed it to use the actual sender in the callout; this means that
222 the cache record is now keyed on a recipient/sender pair, not just the
223 recipient address. There doesn't seem to be a real danger of callout loops,
224 since a callout by the remote host to check the sender would use <>.
227 Version 4.30
228 ------------
230 1. I have abolished timeout_DNS as an error that can be detected in retry
231 rules, because it has never worked. Despite the fact that it has been
232 documented since at least release 1.62, there was no code to support it.
233 If you have used it in your retry rules, you will now get a warning message
234 to the log and panic log. It is now treated as plain "timeout".
236 2. After discussion on the mailing list, Exim no longer adds From:, Date:, or
237 Message-Id: header lines to messages that do not originate locally, that is,
238 messages that have an associated sending host address.
240 3. When looking up a host name from an IP address, Exim now tries the DNS
241 first, and only if that fails does it use gethostbyaddr() (or equivalent).
242 This change was made because on some OS, not all the names are given for
243 addresses with multiple PTR records via the gethostbyaddr() interface. The
244 order of lookup can be changed by setting host_lookup_order.
247 Version 4.23
248 ------------
250 1. The new FIXED_NEVER_USERS build-time option creates a list of "never users"
251 that cannot be overridden. The default in the distributed EDITME is "root".
252 If for some reason you were (against advice) running deliveries as root, you
253 will have to ensure that FIXED_NEVER_USERS is not set in your
254 Local/Makefile.
256 2. The ${quote: operator now quotes an empty string, which it did not before.
258 3. Version 4.23 saves the contents of the ACL variables with the message, so
259 that they can be used later. If one of these variables contains a newline,
260 there will be a newline character in the spool that will not be interpreted
261 correctely by a previous version of Exim. (Exim ignores keyed spool file
262 items that it doesn't understand - precisely for this kind of problem - but
263 it expects them all to be on one line.)
265 So the bottom line is: if you have newlines in your ACL variables, you
266 cannot retreat from 4.23.
269 Version 4.21
270 ------------
272 1. The idea of the "warn" ACL verb is that it adds a header or writes to the
273 log only when "message" or "log_message" are set. However, if one of the
274 conditions was an address verification, or a call to a nested ACL, the
275 messages generated by the underlying test were being passed through. This
276 no longer happens. The underlying message is available in $acl_verify_
277 message for both "message" and "log_message" expansions, so it can be
278 passed through if needed.
280 2. The way that the $h_ (and $header_) expansions work has been changed by the
281 addition of RFC 2047 decoding. See the main documentation (the NewStuff file
282 until release 4.30, then the manual) for full details. Briefly, there are
283 now three forms:
285 $rh_xxx: and $rheader_xxx: give the original content of the header
286 line(s), with no processing at all.
288 $bh_xxx: and $bheader_xxx: remove leading and trailing white space, and
289 then decode base64 or quoted-printable "words" within the header text,
290 but do not do charset translation.
292 $h_xxx: and $header_xxx: attempt to translate the $bh_ string to a
293 standard character set.
295 If you have previously been using $h_ expansions to access the raw
296 characters, you should change to $rh_ instead.
298 3. When Exim creates an RFC 2047 encoded word in a header line, it labels it
299 with the default character set from the headers_charset option instead of
300 always using iso-8859-1.
302 4. If TMPDIR is defined in Local/Makefile (default in src/EDITME is
303 TMPDIR="/tmp"), Exim checks for the presence of an environment variable
304 called TMPDIR, and if it finds it is different, it changes its value.
306 5. Following a discussion on the list, the rules by which Exim recognises line
307 endings on incoming messages have been changed. The -dropcr and drop_cr
308 options are now no-ops, retained only for backwards compatibility. The
309 following line terminators are recognized: LF CRLF CR. However, special
310 processing applies to CR:
312 (i) The sequence CR . CR does *not* terminate an incoming SMTP message,
313 nor a local message in the state where . is a terminator.
315 (ii) If a bare CR is encountered in a header line, an extra space is added
316 after the line terminator so as not to end the header. The reasoning
317 behind this is that bare CRs in header lines are most likely either
318 to be mistakes, or people trying to play silly games.
320 6. The code for using daemon_smtp_port, local_interfaces, and the -oX options
321 has been reorganized. It is supposed to be backwards compatible, but it is
322 mentioned here just in case I've screwed up.
326 Version 4.20
327 ------------
329 1. I have tidied and re-organized the code that uses alarm() for imposing time
330 limits on various things. It shouldn't affect anything, but if you notice
331 processes getting stuck, it may be that I've broken something.
333 2. The "arguments" log selector now also logs the current working directory
334 when Exim is called.
336 3. An incompatible change has been made to the appendfile transport. This
337 affects the case when it is used for file deliveries that are set up by
338 .forward and filter files. Previously, any settings of the "file" or
339 "directory" options were ignored. It is hoped that, like the address_file
340 transport in the default configuration, these options were never in fact set
341 on such transports, because they were of no use.
343 Now, if either of these options is set, it is used. The path that is passed
344 by the router is in $address_file (this is not new), so it can be used as
345 part of a longer path, or modified in any other way that expansion permits.
347 If neither "file" nor "directory" is set, the behaviour is unchanged.
349 4. Related to the above: in a filter, if a "save" command specifies a non-
350 absolute path, the value of $home/ is pre-pended. This no longer happens if
351 $home is unset or is set to an empty string.
353 5. Multiple file deliveries from a filter or .forward file can never be
354 batched; the value of batch_max on the transport is ignored for file
355 deliveries. I'm assuming that nobody ever actually set batch_max on the
356 address_file transport - it would have had odd effects previously.
358 6. DESTDIR is the more common variable that ROOT for use when installing
359 software under a different root filing system. The Exim install script now
360 recognizes DESTDIR first; if it is not set, ROOT is used.
362 7. If DESTDIR is set when installing Exim, it no longer prepends its value to
363 the path of the system aliases file that appears in the default
364 configuration (when a default configuration is installed). If an aliases
365 file is actually created, its name *does* use the prefix.
368 Version 4.14
369 ------------
371 1. The default for the maximum number of unknown SMTP commands that Exim will
372 accept before dropping a connection has been reduced from 5 to 3. However, you
373 can now change the value by setting smtp_max_unknown_commands.
375 2. The ${quote: operator has been changed so that it turns newline and carriage
376 return characters into \n and \r, respectively.
378 3. The file names used for maildir messages now include the microsecond time
379 fraction as well as the time in seconds, to cope with systems where the process
380 id can be re-used within the same second. The format is now
382 <time>.H<microsec>P<pid>.<host>
384 This should be a compatible change, but is noted here just in case.
386 4. The rules for creating message ids have changed, to cope with systems where
387 the process id can be re-used within the same second. The format, however, is
388 unchanged, so this should not cause any problems, except as noted in the next
389 item.
391 5. The maximum value for localhost_number has been reduced from 255 to 16, in
392 order to implement the new message id rules. For operating systems that have
393 case-insensitive file systems (Cygwin and Darwin), the limit is 10.
395 6. verify = header_syntax was allowing unqualified addresses in all cases. Now
396 it allows them only for locally generated messages and from hosts that match
397 sender_unqualified_hosts or recipient_unqualified_hosts, respectively.
399 7. For reasons lost in the mists of time, when a pipe transport was run, the
400 environment variable MESSAGE_ID was set to the message ID preceded by 'E' (the
401 form used in Message-ID: header lines). The 'E' has been removed.
404 Version 4.11
405 ------------
407 1. The handling of lines in the configuration file has changed. Previously,
408 macro expansion was applied to logical lines, after continuations had been
409 joined on. This meant that it could not be used in .include lines, which are
410 handled as physical rather than logical lines. Macro expansion is now done on
411 physical lines rather than logical lines. This means there are two
412 incompatibilities:
414 (a) A macro that expands to # to turn a line into a comment now applies only
415 to the physical line where it appears. Previously, it would have caused
416 any following continuations also to be ignored.
418 (b) A macro name can no longer be split over the boundary between a line and
419 its continuation. Actually, this is more of a bug fix. :-)
421 2. The -D command line option must now all be within one command line item.
422 This makes it possible to use -D to set a macro to the empty string by commands
423 such as
425 exim -DABC ...
426 exim -DABC= ...
428 Previously, these items would have moved on to the next item on the command
429 line. To include spaces in a macro definition item, quotes must be used, in
430 which case you can also have spaces after -D and surrounding the equals. For
431 example:
433 exim '-D ABC = something' ...
435 3. The way that addresses that redirect to themselves are handled has been
436 changed, in order to fix an obscure bug. This should not cause any problems
437 except in the case of wanting to go back from a 4.11 (or later) release to an
438 earlier release. If there are undelivered messages on the spool that contain
439 addresses which redirect to themselves, and the redirected addresses have
440 already been delivered, you might get a duplicate delivery if you revert to an
441 earlier Exim.
443 4. The default way of looking up IP addresses for hosts in the manualroute and
444 queryprogram routers has been changed. If "byname" or "bydns" is explicitly
445 specified, there is no change, but if no method is specified, Exim now behaves
446 as follows:
448 First, a DNS lookup is done. If this yields anything other than
449 HOST_NOT_FOUND, that result is used. Otherwise, Exim goes on to try a call to
450 getipnodebyname() (or gethostbyname() on older systems) and the result of the
451 lookup is the result of that call.
453 This change has been made because it has been discovered that on some systems,
454 if a DNS lookup called via getipnodebyname() times out, HOST_NOT_FOUND is
455 returned instead of TRY_AGAIN. Thus, it is safest to try a DNS lookup directly
456 first, and only if that gives a definite "no such host" to try the local
457 function.
459 5. In fixing the minor security problem with pid_file_path, I have removed some
460 backwards-compatible (undocumented) code which was present to ease conversion
461 from Exim 3. In Exim 4, pid_file_path is a literal; in Exim 3 it was allowed to
462 contain "%s", which was replaced by the port number for daemons listening on
463 non-standard ports. In Exim 4, such daemons do not write a pid file. The
464 backwards compatibility feature was to replace "%s" by nothing if it occurred
465 in an Exim 4 setting of pid_file_path. The bug was in this code. I have solved
466 the problem by removing the backwards compatibility feature. Thus, if you still
467 have "%s" somewhere in a setting of pid_file_path, you should remove it.
469 6. There has been an extension to lsearch files. The keys in these files may
470 now be quoted in order to allow for whitespace and colons in them. This means
471 that if you were previously using keys that began with a doublequote, you will
472 now have to wrap them with extra quotes and escape the internal quotes. The
473 possibility that anybody is actually doing this seems extremely remote, but it
474 is documented just in case.
477 Version 4.10
478 ------------
480 The build-time parameter EXIWHAT_KILL_ARG has been renamed EXIWHAT_KILL_SIGNAL
481 to better reflect its function. The OS-specific files have been updated. Only
482 if you have explicitly set this in your Makefile (highly unlikely) do you need
483 to change anything.
485 ****