1 $Cambridge: exim/src/README.UPDATING,v 1.5 2005/03/08 11:38:21 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. *
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.
34 The format in which GnuTLS parameters are cached (in the file gnutls-params in
35 the spool directory) has been changed. The new format can also be generated
36 externally, so it is now possible to update the values from outside Exim. This
37 has been implemented in an upwards, BUT NOT downwards, compatible manner.
38 Upgrading should be seamless: when Exim finds that it cannot understand an
39 existing cache file, it generates new parameters and writes them to the cache
40 in the new format. If, however, you downgrade from 4.51 to a previous release,
41 you MUST delete the gnutls-params file in the spool directory, because the
42 older Exim will not recognize the new format.
48 The exicyclog script has been updated to use three-digit numbers in rotated log
49 files if the maximum number to keep is greater than 99. If you are already
50 keeping more than 99, there will be an incompatible change when you upgrade.
51 You will probably want to rename your old log files to the new form before
52 running the new exicyclog.
58 RFC 3848 specifies standard names for the "with" phrase in Received: header
59 lines when AUTH and/or TLS are in use. This is the "received protocol"
60 field. Exim used to use "asmtp" for authenticated SMTP, without any
61 indication (in the protocol name) for TLS use. Now it follows the RFC and
62 uses "esmtpa" if the connection is authenticated, "esmtps" if it is
63 encrypted, and "esmtpsa" if it is both encrypted and authenticated. These names
64 appear in log lines as well as in Received: header lines.
70 Change 4.31/2 gave problems to data ACLs and local_scan() functions that
71 expected to see a Received: header. I have changed to yet another scheme. The
72 Received: header is now generated after the body is received, but before the
73 ACL or local_scan() is called. After they have run, the timestamp in the
74 Received: header is updated.
76 Thus, change (a) of 4.31/2 has been reversed, but change (b) is still true,
77 which is lucky, since I decided it was a bug fix.
83 If an expansion in a condition on a "warn" statement fails because a lookup
84 defers, the "warn" statement is abandoned, and the next ACL statement is
85 processed. Previously this caused the whole ACL to be aborted.
91 Change 4.31/2 has been reversed, as it proved contentious. Recipient callout
92 verification now uses <> in the MAIL command by default, as it did before. A
93 new callout option, "use_sender", has been added to request the other
100 1. If you compile Exim to use GnuTLS, it now requires the use of release 1.0.0
101 or greater. The interface to the obsolete 0.8.x releases is no longer
102 supported. There is one externally visible change: the format for the
103 display of Distinguished Names now uses commas as a separator rather than a
104 slash. This is to comply with RFC 2253.
106 2. When a message is received, the Received: header line is now generated when
107 reception is complete, instead of at the start of reception. For messages
108 that take a long time to come in, this changes the meaning of the timestamp.
109 There are several side-effects of this change:
111 (a) If a message is rejected by a DATA or non-SMTP ACL, or by local_scan(),
112 the logged header lines no longer include the local Received: line,
113 because it has not yet been created. If the message is a non-SMTP one,
114 and the error is processed by sending a message to the sender, the copy
115 of the original message that is returned does not have an added
118 (b) When a filter file is tested using -bf, no additional Received: header
119 is added to the test message. After some thought, I decided that this
122 The contents of $received_for are not affected by this change. This
123 variable still contains the single recipient of a message, copied after
124 addresses have been rewritten, but before local_scan() is run.
126 2. Recipient callout verification, like sender verification, was using <> in
127 the MAIL FROM command. This isn't really the right thing, since the actual
128 sender may affect whether the remote host accepts the recipient or not. I
129 have changed it to use the actual sender in the callout; this means that
130 the cache record is now keyed on a recipient/sender pair, not just the
131 recipient address. There doesn't seem to be a real danger of callout loops,
132 since a callout by the remote host to check the sender would use <>.
138 1. I have abolished timeout_DNS as an error that can be detected in retry
139 rules, because it has never worked. Despite the fact that it has been
140 documented since at least release 1.62, there was no code to support it.
141 If you have used it in your retry rules, you will now get a warning message
142 to the log and panic log. It is now treated as plain "timeout".
144 2. After discussion on the mailing list, Exim no longer adds From:, Date:, or
145 Message-Id: header lines to messages that do not originate locally, that is,
146 messages that have an associated sending host address.
148 3. When looking up a host name from an IP address, Exim now tries the DNS
149 first, and only if that fails does it use gethostbyaddr() (or equivalent).
150 This change was made because on some OS, not all the names are given for
151 addresses with multiple PTR records via the gethostbyaddr() interface. The
152 order of lookup can be changed by setting host_lookup_order.
158 1. The new FIXED_NEVER_USERS build-time option creates a list of "never users"
159 that cannot be overridden. The default in the distributed EDITME is "root".
160 If for some reason you were (against advice) running deliveries as root, you
161 will have to ensure that FIXED_NEVER_USERS is not set in your
164 2. The ${quote: operator now quotes an empty string, which it did not before.
166 3. Version 4.23 saves the contents of the ACL variables with the message, so
167 that they can be used later. If one of these variables contains a newline,
168 there will be a newline character in the spool that will not be interpreted
169 correctely by a previous version of Exim. (Exim ignores keyed spool file
170 items that it doesn't understand - precisely for this kind of problem - but
171 it expects them all to be on one line.)
173 So the bottom line is: if you have newlines in your ACL variables, you
174 cannot retreat from 4.23.
180 1. The idea of the "warn" ACL verb is that it adds a header or writes to the
181 log only when "message" or "log_message" are set. However, if one of the
182 conditions was an address verification, or a call to a nested ACL, the
183 messages generated by the underlying test were being passed through. This
184 no longer happens. The underlying message is available in $acl_verify_
185 message for both "message" and "log_message" expansions, so it can be
186 passed through if needed.
188 2. The way that the $h_ (and $header_) expansions work has been changed by the
189 addition of RFC 2047 decoding. See the main documentation (the NewStuff file
190 until release 4.30, then the manual) for full details. Briefly, there are
193 $rh_xxx: and $rheader_xxx: give the original content of the header
194 line(s), with no processing at all.
196 $bh_xxx: and $bheader_xxx: remove leading and trailing white space, and
197 then decode base64 or quoted-printable "words" within the header text,
198 but do not do charset translation.
200 $h_xxx: and $header_xxx: attempt to translate the $bh_ string to a
201 standard character set.
203 If you have previously been using $h_ expansions to access the raw
204 characters, you should change to $rh_ instead.
206 3. When Exim creates an RFC 2047 encoded word in a header line, it labels it
207 with the default character set from the headers_charset option instead of
208 always using iso-8859-1.
210 4. If TMPDIR is defined in Local/Makefile (default in src/EDITME is
211 TMPDIR="/tmp"), Exim checks for the presence of an environment variable
212 called TMPDIR, and if it finds it is different, it changes its value.
214 5. Following a discussion on the list, the rules by which Exim recognises line
215 endings on incoming messages have been changed. The -dropcr and drop_cr
216 options are now no-ops, retained only for backwards compatibility. The
217 following line terminators are recognized: LF CRLF CR. However, special
218 processing applies to CR:
220 (i) The sequence CR . CR does *not* terminate an incoming SMTP message,
221 nor a local message in the state where . is a terminator.
223 (ii) If a bare CR is encountered in a header line, an extra space is added
224 after the line terminator so as not to end the header. The reasoning
225 behind this is that bare CRs in header lines are most likely either
226 to be mistakes, or people trying to play silly games.
228 6. The code for using daemon_smtp_port, local_interfaces, and the -oX options
229 has been reorganized. It is supposed to be backwards compatible, but it is
230 mentioned here just in case I've screwed up.
237 1. I have tidied and re-organized the code that uses alarm() for imposing time
238 limits on various things. It shouldn't affect anything, but if you notice
239 processes getting stuck, it may be that I've broken something.
241 2. The "arguments" log selector now also logs the current working directory
244 3. An incompatible change has been made to the appendfile transport. This
245 affects the case when it is used for file deliveries that are set up by
246 .forward and filter files. Previously, any settings of the "file" or
247 "directory" options were ignored. It is hoped that, like the address_file
248 transport in the default configuration, these options were never in fact set
249 on such transports, because they were of no use.
251 Now, if either of these options is set, it is used. The path that is passed
252 by the router is in $address_file (this is not new), so it can be used as
253 part of a longer path, or modified in any other way that expansion permits.
255 If neither "file" nor "directory" is set, the behaviour is unchanged.
257 4. Related to the above: in a filter, if a "save" command specifies a non-
258 absolute path, the value of $home/ is pre-pended. This no longer happens if
259 $home is unset or is set to an empty string.
261 5. Multiple file deliveries from a filter or .forward file can never be
262 batched; the value of batch_max on the transport is ignored for file
263 deliveries. I'm assuming that nobody ever actually set batch_max on the
264 address_file transport - it would have had odd effects previously.
266 6. DESTDIR is the more common variable that ROOT for use when installing
267 software under a different root filing system. The Exim install script now
268 recognizes DESTDIR first; if it is not set, ROOT is used.
270 7. If DESTDIR is set when installing Exim, it no longer prepends its value to
271 the path of the system aliases file that appears in the default
272 configuration (when a default configuration is installed). If an aliases
273 file is actually created, its name *does* use the prefix.
279 1. The default for the maximum number of unknown SMTP commands that Exim will
280 accept before dropping a connection has been reduced from 5 to 3. However, you
281 can now change the value by setting smtp_max_unknown_commands.
283 2. The ${quote: operator has been changed so that it turns newline and carriage
284 return characters into \n and \r, respectively.
286 3. The file names used for maildir messages now include the microsecond time
287 fraction as well as the time in seconds, to cope with systems where the process
288 id can be re-used within the same second. The format is now
290 <time>.H<microsec>P<pid>.<host>
292 This should be a compatible change, but is noted here just in case.
294 4. The rules for creating message ids have changed, to cope with systems where
295 the process id can be re-used within the same second. The format, however, is
296 unchanged, so this should not cause any problems, except as noted in the next
299 5. The maximum value for localhost_number has been reduced from 255 to 16, in
300 order to implement the new message id rules. For operating systems that have
301 case-insensitive file systems (Cygwin and Darwin), the limit is 10.
303 6. verify = header_syntax was allowing unqualified addresses in all cases. Now
304 it allows them only for locally generated messages and from hosts that match
305 sender_unqualified_hosts or recipient_unqualified_hosts, respectively.
307 7. For reasons lost in the mists of time, when a pipe transport was run, the
308 environment variable MESSAGE_ID was set to the message ID preceded by 'E' (the
309 form used in Message-ID: header lines). The 'E' has been removed.
315 1. The handling of lines in the configuration file has changed. Previously,
316 macro expansion was applied to logical lines, after continuations had been
317 joined on. This meant that it could not be used in .include lines, which are
318 handled as physical rather than logical lines. Macro expansion is now done on
319 physical lines rather than logical lines. This means there are two
322 (a) A macro that expands to # to turn a line into a comment now applies only
323 to the physical line where it appears. Previously, it would have caused
324 any following continuations also to be ignored.
326 (b) A macro name can no longer be split over the boundary between a line and
327 its continuation. Actually, this is more of a bug fix. :-)
329 2. The -D command line option must now all be within one command line item.
330 This makes it possible to use -D to set a macro to the empty string by commands
336 Previously, these items would have moved on to the next item on the command
337 line. To include spaces in a macro definition item, quotes must be used, in
338 which case you can also have spaces after -D and surrounding the equals. For
341 exim '-D ABC = something' ...
343 3. The way that addresses that redirect to themselves are handled has been
344 changed, in order to fix an obscure bug. This should not cause any problems
345 except in the case of wanting to go back from a 4.11 (or later) release to an
346 earlier release. If there are undelivered messages on the spool that contain
347 addresses which redirect to themselves, and the redirected addresses have
348 already been delivered, you might get a duplicate delivery if you revert to an
351 4. The default way of looking up IP addresses for hosts in the manualroute and
352 queryprogram routers has been changed. If "byname" or "bydns" is explicitly
353 specified, there is no change, but if no method is specified, Exim now behaves
356 First, a DNS lookup is done. If this yields anything other than
357 HOST_NOT_FOUND, that result is used. Otherwise, Exim goes on to try a call to
358 getipnodebyname() (or gethostbyname() on older systems) and the result of the
359 lookup is the result of that call.
361 This change has been made because it has been discovered that on some systems,
362 if a DNS lookup called via getipnodebyname() times out, HOST_NOT_FOUND is
363 returned instead of TRY_AGAIN. Thus, it is safest to try a DNS lookup directly
364 first, and only if that gives a definite "no such host" to try the local
367 5. In fixing the minor security problem with pid_file_path, I have removed some
368 backwards-compatible (undocumented) code which was present to ease conversion
369 from Exim 3. In Exim 4, pid_file_path is a literal; in Exim 3 it was allowed to
370 contain "%s", which was replaced by the port number for daemons listening on
371 non-standard ports. In Exim 4, such daemons do not write a pid file. The
372 backwards compatibility feature was to replace "%s" by nothing if it occurred
373 in an Exim 4 setting of pid_file_path. The bug was in this code. I have solved
374 the problem by removing the backwards compatibility feature. Thus, if you still
375 have "%s" somewhere in a setting of pid_file_path, you should remove it.
377 6. There has been an extension to lsearch files. The keys in these files may
378 now be quoted in order to allow for whitespace and colons in them. This means
379 that if you were previously using keys that began with a doublequote, you will
380 now have to wrap them with extra quotes and escape the internal quotes. The
381 possibility that anybody is actually doing this seems extremely remote, but it
382 is documented just in case.
388 The build-time parameter EXIWHAT_KILL_ARG has been renamed EXIWHAT_KILL_SIGNAL
389 to better reflect its function. The OS-specific files have been updated. Only
390 if you have explicitly set this in your Makefile (highly unlikely) do you need
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