The use of forbid_filter_existstest now also locks out ${stat:
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254e032f 1$Cambridge: exim/doc/doc-txt/NewStuff,v 1.59 2005/08/01 15:01:12 ph10 Exp $
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2
3New Features in Exim
4--------------------
5
6This file contains descriptions of new features that have been added to Exim,
7but have not yet made it into the main manual (which is most conveniently
8updated when there is a relatively large batch of changes). The doc/ChangeLog
9file contains a listing of all changes, including bug fixes.
10
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11Exim version 4.53
12-----------------
13
14TK/01 Added the "success_on_redirect" address verification option. When an
15 address generates new addresses during routing, Exim will abort
16 verification with "success" when more than one address has been
17 generated, but continue to verify a single new address. The latter
18 does not happen when the new "success_on_redirect" option is set, like
19
20 require verify = recipient/success_on_redirect/callout=10s
21
22 In that case, verification will succeed when a router generates a new
23 address.
24
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25PH/01 Support for SQLite database lookups has been added. This is another
26 query-style lookup, but it is slightly different from the others because
27 a file name is required in addition to the SQL query. This is because an
28 SQLite database is a single file and there is no daemon as in other SQL
29 databases. The interface to Exim requires the name of the file, as an
30 absolute path, to be given at the start of the query. It is separated
31 from the query by white space. This means that the path name cannot
32 contain white space. Here is a lookup expansion example:
33
34 ${lookup sqlite {/some/thing/sqlitedb \
35 select name from aliases where id='ph10';}}
36
37 In a list, the syntax is similar. For example:
38
39 domainlist relay_domains = sqlite;/some/thing/sqlitedb \
40 select * from relays where ip='$sender_host_address';
41
42 The only character affected by the ${quote_sqlite: operator is a single
43 quote, which it doubles.
44
45 Note that you must set LOOKUP_SQLITE=yes in Local/Makefile in order to
46 obtain SQLite support, and you will also need to add -lsqlite3 to the
47 EXTRALIBS setting. And of course, you have to install SQLite on your
48 host first.
49
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50PH/02 The variable $message_id is now deprecated, to be replaced by
51 $message_exim_id, which makes it clearer which ID is being referenced.
52
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53PH/03 The use of forbid_filter_existstest now also locks out the use of the
54 ${stat: expansion item.
55
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57Exim version 4.52
58-----------------
59
60TF/01 Support for checking Client SMTP Authorization has been added. CSA is a
61 system which allows a site to advertise which machines are and are not
62 permitted to send email. This is done by placing special SRV records in
63 the DNS, which are looked up using the client's HELO domain. At this
64 time CSA is still an Internet-Draft.
65
66 Client SMTP Authorization checks are performed by the ACL condition
67 verify=csa. This will fail if the client is not authorized. If there is
68 a DNS problem, or if no valid CSA SRV record is found, or if the client
69 is authorized, the condition succeeds. These three cases can be
70 distinguished using the expansion variable $csa_status, which can take
71 one of the values "fail", "defer", "unknown", or "ok". The condition
72 does not itself defer because that would be likely to cause problems
73 for legitimate email.
74
75 The error messages produced by the CSA code include slightly more
76 detail. If $csa_status is "defer" this may be because of problems
77 looking up the CSA SRV record, or problems looking up the CSA target
78 address record. There are four reasons for $csa_status being "fail":
79 the client's host name is explicitly not authorized; the client's IP
80 address does not match any of the CSA target IP addresses; the client's
81 host name is authorized but it has no valid target IP addresses (e.g.
82 the target's addresses are IPv6 and the client is using IPv4); or the
83 client's host name has no CSA SRV record but a parent domain has
84 asserted that all subdomains must be explicitly authorized.
85
86 The verify=csa condition can take an argument which is the domain to
87 use for the DNS query. The default is verify=csa/$sender_helo_name.
88
89 This implementation includes an extension to CSA. If the query domain
90 is an address literal such as [192.0.2.95], or if it is a bare IP
91 address, Exim will search for CSA SRV records in the reverse DNS as if
92 the HELO domain was e.g. 95.2.0.192.in-addr.arpa. Therefore it is
93 meaningful to say, for example, verify=csa/$sender_host_address - in
94 fact, this is the check that Exim performs if the client does not say
95 HELO. This extension can be turned off by setting the main
96 configuration option dns_csa_use_reverse = false.
97
98 If a CSA SRV record is not found for the domain itself, then a search
99 is performed through its parent domains for a record which might be
100 making assertions about subdomains. The maximum depth of this search is
101 limited using the main configuration option dns_csa_search_limit, which
102 takes the value 5 by default. Exim does not look for CSA SRV records in
103 a top level domain, so the default settings handle HELO domains as long
104 as seven (hostname.five.four.three.two.one.com) which encompasses the
105 vast majority of legitimate HELO domains.
106
107 The dnsdb lookup also has support for CSA. Although dnsdb already
108 supports SRV lookups, this is not sufficient because of the extra
109 parent domain search behaviour of CSA, and (as with PTR lookups)
110 dnsdb also turns IP addresses into lookups in the reverse DNS space.
111 The result of ${lookup dnsdb {csa=$sender_helo_name} } has two
112 space-separated fields: an authorization code and a target host name.
113 The authorization code can be "Y" for yes, "N" for no, "X" for explicit
114 authorization required but absent, or "?" for unknown.
115
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116PH/01 The amount of output produced by the "make" process has been reduced,
117 because the compile lines are often rather long, making it all pretty
118 unreadable. The new style is along the lines of the 2.6 Linux kernel:
119 just a short line for each module that is being compiled or linked.
120 However, it is still possible to get the full output, by calling "make"
121 like this:
122
123 FULLECHO='' make -e
124
125 The value of FULLECHO defaults to "@", the flag character that suppresses
126 command reflection in "make". When you ask for the full output, it is
127 given in addition to the the short output.
128
4df1e33e 129TF/02 There have been two changes concerned with submission mode:
87ba3f5f 130
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131 Until now submission mode always left the return path alone, whereas
132 locally-submitted messages from untrusted users have the return path
133 fixed to the user's email address. Submission mode now fixes the return
134 path to the same address as is used to create the Sender: header. If
135 /sender_retain is specified then both the Sender: header and the return
136 path are left alone.
87ba3f5f 137
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138 Note that the changes caused by submission mode take effect after the
139 predata ACL. This means that any sender checks performed before the
140 fix-ups will use the untrusted sender address specified by the user, not
141 the trusted sender address specified by submission mode. Although this
142 might be slightly unexpected, it does mean that you can configure ACL
143 checks to spot that a user is trying to spoof another's address, for
144 example.
87ba3f5f 145
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146 There is also a new /name= option for submission mode which allows you
147 to specify the user's full name to be included in the Sender: header.
148 For example:
149
150 accept authenticated = *
151 control = submission/name=${lookup {$authenticated_id} \
152 lsearch {/etc/exim/namelist} }
153
154 The namelist file contains entries like
155
156 fanf: Tony Finch
157
158 And the resulting Sender: header looks like
159
160 Sender: Tony Finch <fanf@exim.org>
161
162TF/03 The control = fakereject ACL modifier now has a fakedefer counterpart,
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163 which works in exactly the same way except it causes a fake SMTP 450
164 response after the message data instead of a fake SMTP 550 response.
165 You must take care when using fakedefer because it will cause messages
166 to be duplicated when the sender retries. Therefore you should not use
167 fakedefer if the message will be delivered normally.
168
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169TF/04 There is a new ratelimit ACL condition which can be used to measure
170 and control the rate at which clients can send email. This is more
171 powerful than the existing smtp_ratelimit_* options, because those
172 options only control the rate of commands in a single SMTP session,
173 whereas the new ratelimit condition works across all connections
174 (concurrent and sequential) to the same host.
175
176 The syntax of the ratelimit condition is:
177
178 ratelimit = <m> / <p> / <options> / <key>
179
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180 If the average client sending rate is less than m messages per time
181 period p then the condition is false, otherwise it is true.
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182
183 The parameter p is the smoothing time constant, in the form of an Exim
184 time interval e.g. 8h for eight hours. A larger time constant means it
185 takes Exim longer to forget a client's past behaviour. The parameter m is
186 the maximum number of messages that a client can send in a fast burst. By
187 increasing both m and p but keeping m/p constant, you can allow a client
188 to send more messages in a burst without changing its overall sending
189 rate limit. Conversely, if m and p are both small then messages must be
190 sent at an even rate.
191
192 The key is used to look up the data used to calcluate the client's
193 average sending rate. This data is stored in a database maintained by
194 Exim in its spool directory alongside the retry database etc. For
195 example, you can limit the sending rate of each authenticated user,
196 independent of the computer they are sending from, by setting the key
197 to $authenticated_id. The default key is $sender_host_address.
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198 Internally, Exim includes the smoothing constant p and the options in
199 the lookup key because they alter the meaning of the stored data.
200 This is not true for the limit m, so you can alter the configured
201 maximum rate and Exim will still remember clients' past behaviour,
202 but if you alter the other ratelimit parameters Exim will effectively
203 forget their past behaviour.
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204
205 Each ratelimit condition can have up to two options. The first option
206 specifies what Exim measures the rate of, and the second specifies how
207 Exim handles excessively fast clients.
208
209 The per_mail option means that it measures the client's rate of sending
210 messages. This is the default if none of the per_* options is specified.
211
212 The per_conn option means that it measures the client's connection rate.
213
214 The per_byte option limits the sender's email bandwidth. Note that it
215 is best to use this option in the DATA ACL; if it is used in an earlier
216 ACL it relies on the SIZE parameter on the MAIL command, which may be
217 inaccurate or completely missing. You can follow the limit m in the
218 configuration with K, M, or G to specify limits in kilobytes,
219 megabytes, or gigabytes respectively.
220
221 The per_cmd option means that Exim recomputes the rate every time the
222 condition is processed, which can be used to limit the SMTP command rate.
223 The alias per_rcpt is provided for use in the RCPT ACL instead of per_cmd
224 to make it clear that the effect is to limit the rate at which recipients
225 are accepted. Note that in this case the rate limiting engine will see a
226 message with many recipients as a large high-speed burst.
227
228 If a client's average rate is greater than the maximum, the rate
229 limiting engine can react in two possible ways, depending on the
230 presence of the strict or leaky options. This is independent of the
231 other counter-measures (e.g. rejecting the message) that may be
232 specified by the rest of the ACL. The default mode is leaky, which
233 avoids a sender's over-aggressive retry rate preventing it from getting
234 any email through.
235
236 The strict option means that the client's recorded rate is always
237 updated. The effect of this is that Exim measures the client's average
238 rate of attempts to send email, which can be much higher than the
239 maximum. If the client is over the limit it will be subjected to
240 counter-measures until it slows down below the maximum rate.
241
242 The leaky option means that the client's recorded rate is not updated
243 if it is above the limit. The effect of this is that Exim measures the
244 client's average rate of successfully sent email, which cannot be
245 greater than the maximum. If the client is over the limit it will
246 suffer some counter-measures, but it will still be able to send email
247 at the configured maximum rate, whatever the rate of its attempts.
248
249 As a side-effect, the ratelimit condition will set the expansion
250 variables $sender_rate containing the client's computed rate,
251 $sender_rate_limit containing the configured value of m, and
252 $sender_rate_period containing the configured value of p.
253
254 Exim's other ACL facilities are used to define what counter-measures
255 are taken when the rate limit is exceeded. This might be anything from
256 logging a warning (e.g. while measuring existing sending rates in order
257 to define our policy), through time delays to slow down fast senders,
258 up to rejecting the message. For example,
259
260 # Log all senders' rates
261 warn
262 ratelimit = 0 / 1h / strict
263 log_message = \
264 Sender rate $sender_rate > $sender_rate_limit / $sender_rate_period
265
266 # Slow down fast senders
267 warn
268 ratelimit = 100 / 1h / per_rcpt / strict
269 delay = ${eval: 10 * ($sender_rate - $sender_rate_limit) }
270
271 # Keep authenticated users under control
272 deny
273 ratelimit = 100 / 1d / strict / $authenticated_id
274
275 # System-wide rate limit
276 defer
277 message = Sorry, too busy. Try again later.
278 ratelimit = 10 / 1s / $primary_hostname
279
280 # Restrict incoming rate from each host, with a default rate limit
281 # set using a macro and special cases looked up in a table.
282 defer
283 message = Sender rate $sender_rate exceeds \
284 $sender_rate_limit messages per $sender_rate_period
285 ratelimit = ${lookup {$sender_host_address} \
286 cdb {DB/ratelimits.cdb} \
287 {$value} {RATELIMIT} }
288
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289 Warning: if you have a busy server with a lot of ratelimit tests,
290 especially with the per_rcpt option, you may suffer from a performance
291 bottleneck caused by locking on the ratelimit hints database. Apart from
292 making your ACLs less complicated, you can reduce the problem by using a
293 RAM disk for Exim's hints directory, /var/spool/exim/db/. However this
294 means that Exim will lose its hints data after a reboot (including retry
295 hints, the callout cache, and ratelimit data).
296
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297TK/01 Added an 'spf' lookup type that will return an SPF result for a given
298 email address (the key) and an IP address (the database):
299
300 ${lookup {tom@duncanthrax.net} spf{217.115.139.137}}
301
302 The lookup will return the same result strings as they can appear in
303 $spf_result (pass,fail,softfail,neutral,none,err_perm,err_temp). The
304 lookup is armored in EXPERIMENTAL_SPF. Currently, only IPv4 addresses
305 are supported.
306
307 Patch submitted by Chris Webb <chris@arachsys.com>.
308
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309PH/02 There's a new verify callout option, "fullpostmaster", which first acts
310 as "postmaster" and checks the recipient <postmaster@domain>. If that
311 fails, it tries just <postmaster>, without a domain, in accordance with
312 the specification in RFC 2821.
313
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314PH/03 The action of the auto_thaw option has been changed. It no longer applies
315 to frozen bounce messages.
316
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317TK/02 There are two new expansion items to help with the implementation of
318 the BATV "prvs" scheme in an Exim configuration:
319
320
321 ${prvs {<ADDRESS>}{<KEY>}{[KEYNUM]}}
322
323 The "prvs" expansion item takes three arguments: A qualified RFC2821
324 email address, a key and an (optional) key number. All arguments are
325 expanded before being used, so it is easily possible to lookup a key
326 and key number using the address as the lookup key. The key number is
327 optional and defaults to "0". The item will expand to a "prvs"-signed
328 email address, to be typically used with the "return_path" option on
329 a smtp transport. The decision if BATV should be used with a given
330 sender/recipient pair should be done on router level, to avoid having
331 to set "max_rcpt = 1" on the transport.
332
333
334 ${prvscheck {<ADDRESS>}{<SECRET>}{<RETURN_STRING>}}
335
336 The "prvscheck" expansion item takes three arguments. Argument 1 is
337 expanded first. When the expansion does not yield a SYNTACTICALLY
338 valid "prvs"-scheme address, the whole "prvscheck" item expands to
339 the empty string. If <ADDRESS> is a "prvs"-encoded address after
340 expansion, two expansion variables are set up:
341
342 $prvscheck_address Contains the "prvs"-decoded version of
343 the address from argument 1.
344
345 $prvscheck_keynum Contains the key number extracted from
346 the "prvs"-address in argument 1.
347
348 These two variables can be used in the expansion code of argument 2
349 to retrieve the <SECRET>. The VALIDITY of the "prvs"-signed address
350 is then checked. The result is stored in yet another expansion
351 variable:
352
353 $prvscheck_result Contains the result of a "prvscheck"
354 expansion: Unset (the empty string) for
355 failure, "1" for success.
356
357 The "prvscheck" expansion expands to the empty string if <ADDRESS>
358 is not a SYNTACTICALLY valid "prvs"-scheme address. Otherwise,
359 argument 3 defines what "prvscheck" expands to: If argument 3
360 is the empty string, "prvscheck" expands to the decoded version
361 of the address (no matter if it is CRYPTOGRAPHICALLY valid or not).
362 If argument 3 expands to a non-empty string, "prvscheck" expands
363 to that string.
364
365
366 Usage example
367 -------------
368
369 Macro:
370
371 PRVSCHECK_SQL = ${lookup mysql{SELECT secret FROM batv_prvs WHERE \
372 sender='${quote_mysql:$prvscheck_address}'}{$value}}
373
374 RCPT ACL:
375
376 # Bounces: drop unsigned addresses for BATV senders
377 deny message = This address does not send an unsigned reverse path.
378 senders = :
379 recipients = +batv_recipients
380
381 # Bounces: In case of prvs-signed address, check signature.
382 deny message = Invalid reverse path signature.
383 senders = :
384 condition = ${prvscheck {$local_part@$domain}{PRVSCHECK_SQL}{1}}
385 !condition = $prvscheck_result
386
387 Top-Level Router:
388
389 batv_redirect:
390 driver = redirect
391 data = ${prvscheck {$local_part@$domain}{PRVSCHECK_SQL}{}}
392
393 Transport (referenced by router that makes decision if
394 BATV is applicable):
395
396 external_smtp_batv:
397 driver = smtp
398 return_path = ${prvs {$return_path} \
399 {${lookup mysql{SELECT \
400 secret FROM batv_prvs WHERE \
401 sender='${quote_mysql:$sender_address}'} \
402 {$value}fail}}}
403
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404PH/04 There are two new options that control the retrying done by the daemon
405 at startup when it cannot immediately bind a socket (typically because
406 the socket is already in use). The default values reproduce what were
407 built-in constants previously: daemon_startup_retries defines the number
408 of retries after the first failure (default 9); daemon_startup_sleep
409 defines the length of time to wait between retries (default 30s).
0cd68797 410
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411PH/05 There is now a new ${if condition called "match_ip". It is similar to
412 match_domain, etc. It must be followed by two argument strings. The first
413 (after expansion) must be an IP address or an empty string. The second
414 (after expansion) is a restricted host list that can match only an IP
415 address, not a host name. For example:
416
417 ${if match_ip{$sender_host_address}{1.2.3.4:5.6.7.8}{...}{...}}
418
419 The specific types of host list item that are permitted in the list are
420 shown below. Consult the manual section on host lists for further
421 details.
422
423 . An IP address, optionally with a CIDR mask.
424
425 . A single asterisk matches any IP address.
426
427 . An empty item matches only if the IP address is empty. This could be
428 useful for testing for a locally submitted message or one from specific
429 hosts in a single test such as
430
431 ${if match_ip{$sender_host_address}{:4.3.2.1:...}{...}{...}}
432
433 where the first item in the list is the empty string.
434
435 . The item @[] matches any of the local host's interface addresses.
436
437 . Lookups are assumed to be "net-" style lookups, even if "net-" is not
438 specified. Thus, the following are equivalent:
439
440 ${if match_ip{$sender_host_address}{lsearch;/some/file}...
441 ${if match_ip{$sender_host_address}{net-lsearch;/some/file}...
442
443 You do need to specify the "net-" prefix if you want to specify a
444 specific address mask, for example, by using "net24-".
445
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446PH/06 The "+all" debug selector used to set the flags for all possible output;
447 it is something that people tend to use semi-automatically when
448 generating debug output for me or for the list. However, by including
449 "+memory", an awful lot of output that is very rarely of interest was
450 generated. I have changed this so that "+all" no longer includes
451 "+memory". However, "-all" still turns everything off.
452
e5a9dba6 453
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454Version 4.51
455------------
456
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457PH/01 The format in which GnuTLS parameters are written to the gnutls-param
458 file in the spool directory has been changed. This change has been made
459 to alleviate problems that some people had with the generation of the
460 parameters by Exim when /dev/random was exhausted. In this situation,
461 Exim would hang until /dev/random acquired some more entropy.
462
463 The new code exports and imports the DH and RSA parameters in PEM
464 format. This means that the parameters can be generated externally using
465 the certtool command that is part of GnuTLS.
466
467 To replace the parameters with new ones, instead of deleting the file
468 and letting Exim re-create it, you can generate new parameters using
469 certtool and, when this has been done, replace Exim's cache file by
470 renaming. The relevant commands are something like this:
471
472 # rm -f new.params
473 # touch new.params
474 # chown exim:exim new.params
475 # chmod 0400 new.params
476 # certtool --generate-privkey --bits 512 >new.params
477 # echo "" >>new.params
478 # certtool --generate-dh-params --bits 1024 >> new.params
479 # mv new.params params
480
481 If Exim never has to generate the parameters itself, the possibility of
482 stalling is removed.
483
484PH/02 A new expansion item for dynamically loading and calling a locally-
485 written C function is now provided, if Exim is compiled with
486
487 EXPAND_DLFUNC=yes
488
489 set in Local/Makefile. The facility is not included by default (a
490 suitable error is given if you try to use it when it is not there.)
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491
492 If you enable EXPAND_DLFUNC, you should also be aware of the new redirect
493 router option forbid_filter_dlfunc. If you have unprivileged users on
494 your system who are permitted to create filter files, you might want to
495 set forbid_filter_dlfunc=true in the appropriate router, to stop them
496 using ${dlfunc to run code within Exim.
497
498 You load and call an external function like this:
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499
500 ${dlfunc{/some/file}{function}{arg1}{arg2}...}
501
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502 Once loaded, Exim remembers the dynamically loaded object so that it
503 doesn't reload the same object file in the same Exim process (but of
504 course Exim does start new processes frequently).
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505
506 There may be from zero to eight arguments to the function. When compiling
507 a local function that is to be called in this way, local_scan.h should be
508 included. The Exim variables and functions that are defined by that API
509 are also available for dynamically loaded functions. The function itself
510 must have the following type:
511
512 int dlfunction(uschar **yield, int argc, uschar *argv[])
513
514 Where "uschar" is a typedef for "unsigned char" in local_scan.h. The
515 function should return one of the following values:
516
517 OK Success. The string that is placed in "yield" is put into
518 the expanded string that is being built.
519
520 FAIL A non-forced expansion failure occurs, with the error
521 message taken from "yield", if it is set.
522
523 FAIL_FORCED A forced expansion failure occurs, with the error message
524 taken from "yield" if it is set.
525
526 ERROR Same as FAIL, except that a panic log entry is written.
527
528 When compiling a function that is to be used in this way with gcc,
529 you need to add -shared to the gcc command. Also, in the Exim build-time
530 configuration, you must add -export-dynamic to EXTRALIBS.
b5aea5e1 531
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532TF/01 $received_time is a new expansion variable containing the time and date
533 as a number of seconds since the start of the Unix epoch when the
534 current message was received.
b5aea5e1 535
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536PH/03 There is a new value for RADIUS_LIB_TYPE that can be set in
537 Local/Makefile. It is RADIUSCLIENTNEW, and it requests that the new API,
538 in use from radiusclient 0.4.0 onwards, be used. It does not appear to be
539 possible to detect the different versions automatically.
540
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541PH/04 There is a new option called acl_not_smtp_mime that allows you to scan
542 MIME parts in non-SMTP messages. It operates in exactly the same way as
543 acl_smtp_mime
544
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545PH/05 It is now possible to redefine a macro within the configuration file.
546 The macro must have been previously defined within the configuration (or
547 an included file). A definition on the command line using the -D option
548 causes all definitions and redefinitions within the file to be ignored.
549 In other words, -D overrides any values that are set in the file.
550 Redefinition is specified by using '==' instead of '='. For example:
551
552 MAC1 = initial value
553 ...
554 MAC1 == updated value
555
556 Redefinition does not alter the order in which the macros are applied to
557 the subsequent lines of the configuration file. It is still the same
558 order in which the macros were originally defined. All that changes is
559 the macro's value. Redefinition makes it possible to accumulate values.
560 For example:
561
562 MAC1 = initial value
563 ...
564 MAC1 == MAC1 and something added
565
566 This can be helpful in situations where the configuration file is built
567 from a number of other files.
568
569PH/06 Macros may now be defined or redefined between router, transport,
570 authenticator, or ACL definitions, as well as in the main part of the
571 configuration. They may not, however, be changed within an individual
572 driver or ACL, or in the local_scan, retry, or rewrite sections of the
573 configuration.
574
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575PH/07 $acl_verify_message is now set immediately after the failure of a
576 verification in an ACL, and so is available in subsequent modifiers. In
577 particular, the message can be preserved by coding like this:
578
579 warn !verify = sender
580 set acl_m0 = $acl_verify_message
581
582 Previously, $acl_verify_message was set only while expanding "message"
583 and "log_message" when a very denied access.
584
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585PH/08 The redirect router has two new options, sieve_useraddress and
586 sieve_subaddress. These are passed to a Sieve filter to specify the :user
587 and :subaddress parts of an address. Both options are unset by default.
588 However, when a Sieve filter is run, if sieve_useraddress is unset, the
589 entire original local part (including any prefix or suffix) is used for
590 :user. An unset subaddress is treated as an empty subaddress.
475fe28a 591
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592PH/09 Quota values can be followed by G as well as K and M.
593
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594PH/10 $message_linecount is a new variable that contains the total number of
595 lines in the header and body of the message. Compare $body_linecount,
596 which is the count for the body only. During the DATA and
597 content-scanning ACLs, $message_linecount contains the number of lines
598 received. Before delivery happens (that is, before filters, routers, and
599 transports run) the count is increased to include the Received: header
600 line that Exim standardly adds, and also any other header lines that are
601 added by ACLs. The blank line that separates the message header from the
602 body is not counted. Here is an example of the use of this variable in a
603 DATA ACL:
604
605 deny message = Too many lines in message header
606 condition = \
607 ${if <{250}{${eval: $message_linecount - $body_linecount}}}
608
609 In the MAIL and RCPT ACLs, the value is zero because at that stage the
610 message has not yet been received.
611
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612PH/11 In a ${run expansion, the variable $value (which contains the standard
613 output) is now also usable in the "else" string.
614
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615PH/12 In a pipe transport, although a timeout while waiting for the pipe
616 process to complete was treated as a delivery failure, a timeout while
617 writing the message to the pipe was logged, but erroneously treated as a
618 successful delivery. Such timeouts include transport filter timeouts. For
619 consistency with the overall process timeout, these timeouts are now
620 treated as errors, giving rise to delivery failures by default. However,
621 there is now a new Boolean option for the pipe transport called
622 timeout_defer, which, if set TRUE, converts the failures into defers for
623 both kinds of timeout. A transport filter timeout is now identified in
624 the log output.
625
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f7b63901 627Version 4.50
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628------------
629
b9e40c51 630The documentation is up-to-date for the 4.50 release.
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631
632****