Add $message_exim_id as a synonym for $message_id, which will now be
[exim.git] / doc / doc-txt / NewStuff
1ab52c69 1$Cambridge: exim/doc/doc-txt/NewStuff,v 1.58 2005/08/01 14:00:34 ph10 Exp $
3New Features in Exim
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.
11Exim version 4.53
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
20 require verify = recipient/success_on_redirect/callout=10s
22 In that case, verification will succeed when a router generates a new
23 address.
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:
34 ${lookup sqlite {/some/thing/sqlitedb \
35 select name from aliases where id='ph10';}}
37 In a list, the syntax is similar. For example:
39 domainlist relay_domains = sqlite;/some/thing/sqlitedb \
40 select * from relays where ip='$sender_host_address';
42 The only character affected by the ${quote_sqlite: operator is a single
43 quote, which it doubles.
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.
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.
495ae4b0 53
54Exim version 4.52
57TF/01 Support for checking Client SMTP Authorization has been added. CSA is a
58 system which allows a site to advertise which machines are and are not
59 permitted to send email. This is done by placing special SRV records in
60 the DNS, which are looked up using the client's HELO domain. At this
61 time CSA is still an Internet-Draft.
63 Client SMTP Authorization checks are performed by the ACL condition
64 verify=csa. This will fail if the client is not authorized. If there is
65 a DNS problem, or if no valid CSA SRV record is found, or if the client
66 is authorized, the condition succeeds. These three cases can be
67 distinguished using the expansion variable $csa_status, which can take
68 one of the values "fail", "defer", "unknown", or "ok". The condition
69 does not itself defer because that would be likely to cause problems
70 for legitimate email.
72 The error messages produced by the CSA code include slightly more
73 detail. If $csa_status is "defer" this may be because of problems
74 looking up the CSA SRV record, or problems looking up the CSA target
75 address record. There are four reasons for $csa_status being "fail":
76 the client's host name is explicitly not authorized; the client's IP
77 address does not match any of the CSA target IP addresses; the client's
78 host name is authorized but it has no valid target IP addresses (e.g.
79 the target's addresses are IPv6 and the client is using IPv4); or the
80 client's host name has no CSA SRV record but a parent domain has
81 asserted that all subdomains must be explicitly authorized.
83 The verify=csa condition can take an argument which is the domain to
84 use for the DNS query. The default is verify=csa/$sender_helo_name.
86 This implementation includes an extension to CSA. If the query domain
87 is an address literal such as [], or if it is a bare IP
88 address, Exim will search for CSA SRV records in the reverse DNS as if
89 the HELO domain was e.g. Therefore it is
90 meaningful to say, for example, verify=csa/$sender_host_address - in
91 fact, this is the check that Exim performs if the client does not say
92 HELO. This extension can be turned off by setting the main
93 configuration option dns_csa_use_reverse = false.
95 If a CSA SRV record is not found for the domain itself, then a search
96 is performed through its parent domains for a record which might be
97 making assertions about subdomains. The maximum depth of this search is
98 limited using the main configuration option dns_csa_search_limit, which
99 takes the value 5 by default. Exim does not look for CSA SRV records in
100 a top level domain, so the default settings handle HELO domains as long
101 as seven ( which encompasses the
102 vast majority of legitimate HELO domains.
104 The dnsdb lookup also has support for CSA. Although dnsdb already
105 supports SRV lookups, this is not sufficient because of the extra
106 parent domain search behaviour of CSA, and (as with PTR lookups)
107 dnsdb also turns IP addresses into lookups in the reverse DNS space.
108 The result of ${lookup dnsdb {csa=$sender_helo_name} } has two
109 space-separated fields: an authorization code and a target host name.
110 The authorization code can be "Y" for yes, "N" for no, "X" for explicit
111 authorization required but absent, or "?" for unknown.
113PH/01 The amount of output produced by the "make" process has been reduced,
114 because the compile lines are often rather long, making it all pretty
115 unreadable. The new style is along the lines of the 2.6 Linux kernel:
116 just a short line for each module that is being compiled or linked.
117 However, it is still possible to get the full output, by calling "make"
118 like this:
120 FULLECHO='' make -e
122 The value of FULLECHO defaults to "@", the flag character that suppresses
123 command reflection in "make". When you ask for the full output, it is
124 given in addition to the the short output.
4df1e33e 126TF/02 There have been two changes concerned with submission mode:
87ba3f5f 127
128 Until now submission mode always left the return path alone, whereas
129 locally-submitted messages from untrusted users have the return path
130 fixed to the user's email address. Submission mode now fixes the return
131 path to the same address as is used to create the Sender: header. If
132 /sender_retain is specified then both the Sender: header and the return
133 path are left alone.
87ba3f5f 134
135 Note that the changes caused by submission mode take effect after the
136 predata ACL. This means that any sender checks performed before the
137 fix-ups will use the untrusted sender address specified by the user, not
138 the trusted sender address specified by submission mode. Although this
139 might be slightly unexpected, it does mean that you can configure ACL
140 checks to spot that a user is trying to spoof another's address, for
141 example.
87ba3f5f 142
143 There is also a new /name= option for submission mode which allows you
144 to specify the user's full name to be included in the Sender: header.
145 For example:
147 accept authenticated = *
148 control = submission/name=${lookup {$authenticated_id} \
149 lsearch {/etc/exim/namelist} }
151 The namelist file contains entries like
153 fanf: Tony Finch
155 And the resulting Sender: header looks like
157 Sender: Tony Finch <>
159TF/03 The control = fakereject ACL modifier now has a fakedefer counterpart,
160 which works in exactly the same way except it causes a fake SMTP 450
161 response after the message data instead of a fake SMTP 550 response.
162 You must take care when using fakedefer because it will cause messages
163 to be duplicated when the sender retries. Therefore you should not use
164 fakedefer if the message will be delivered normally.
166TF/04 There is a new ratelimit ACL condition which can be used to measure
167 and control the rate at which clients can send email. This is more
168 powerful than the existing smtp_ratelimit_* options, because those
169 options only control the rate of commands in a single SMTP session,
170 whereas the new ratelimit condition works across all connections
171 (concurrent and sequential) to the same host.
173 The syntax of the ratelimit condition is:
175 ratelimit = <m> / <p> / <options> / <key>
177 If the average client sending rate is less than m messages per time
178 period p then the condition is false, otherwise it is true.
180 The parameter p is the smoothing time constant, in the form of an Exim
181 time interval e.g. 8h for eight hours. A larger time constant means it
182 takes Exim longer to forget a client's past behaviour. The parameter m is
183 the maximum number of messages that a client can send in a fast burst. By
184 increasing both m and p but keeping m/p constant, you can allow a client
185 to send more messages in a burst without changing its overall sending
186 rate limit. Conversely, if m and p are both small then messages must be
187 sent at an even rate.
189 The key is used to look up the data used to calcluate the client's
190 average sending rate. This data is stored in a database maintained by
191 Exim in its spool directory alongside the retry database etc. For
192 example, you can limit the sending rate of each authenticated user,
193 independent of the computer they are sending from, by setting the key
194 to $authenticated_id. The default key is $sender_host_address.
195 Internally, Exim includes the smoothing constant p and the options in
196 the lookup key because they alter the meaning of the stored data.
197 This is not true for the limit m, so you can alter the configured
198 maximum rate and Exim will still remember clients' past behaviour,
199 but if you alter the other ratelimit parameters Exim will effectively
200 forget their past behaviour.
202 Each ratelimit condition can have up to two options. The first option
203 specifies what Exim measures the rate of, and the second specifies how
204 Exim handles excessively fast clients.
206 The per_mail option means that it measures the client's rate of sending
207 messages. This is the default if none of the per_* options is specified.
209 The per_conn option means that it measures the client's connection rate.
211 The per_byte option limits the sender's email bandwidth. Note that it
212 is best to use this option in the DATA ACL; if it is used in an earlier
213 ACL it relies on the SIZE parameter on the MAIL command, which may be
214 inaccurate or completely missing. You can follow the limit m in the
215 configuration with K, M, or G to specify limits in kilobytes,
216 megabytes, or gigabytes respectively.
218 The per_cmd option means that Exim recomputes the rate every time the
219 condition is processed, which can be used to limit the SMTP command rate.
220 The alias per_rcpt is provided for use in the RCPT ACL instead of per_cmd
221 to make it clear that the effect is to limit the rate at which recipients
222 are accepted. Note that in this case the rate limiting engine will see a
223 message with many recipients as a large high-speed burst.
225 If a client's average rate is greater than the maximum, the rate
226 limiting engine can react in two possible ways, depending on the
227 presence of the strict or leaky options. This is independent of the
228 other counter-measures (e.g. rejecting the message) that may be
229 specified by the rest of the ACL. The default mode is leaky, which
230 avoids a sender's over-aggressive retry rate preventing it from getting
231 any email through.
233 The strict option means that the client's recorded rate is always
234 updated. The effect of this is that Exim measures the client's average
235 rate of attempts to send email, which can be much higher than the
236 maximum. If the client is over the limit it will be subjected to
237 counter-measures until it slows down below the maximum rate.
239 The leaky option means that the client's recorded rate is not updated
240 if it is above the limit. The effect of this is that Exim measures the
241 client's average rate of successfully sent email, which cannot be
242 greater than the maximum. If the client is over the limit it will
243 suffer some counter-measures, but it will still be able to send email
244 at the configured maximum rate, whatever the rate of its attempts.
246 As a side-effect, the ratelimit condition will set the expansion
247 variables $sender_rate containing the client's computed rate,
248 $sender_rate_limit containing the configured value of m, and
249 $sender_rate_period containing the configured value of p.
251 Exim's other ACL facilities are used to define what counter-measures
252 are taken when the rate limit is exceeded. This might be anything from
253 logging a warning (e.g. while measuring existing sending rates in order
254 to define our policy), through time delays to slow down fast senders,
255 up to rejecting the message. For example,
257 # Log all senders' rates
258 warn
259 ratelimit = 0 / 1h / strict
260 log_message = \
261 Sender rate $sender_rate > $sender_rate_limit / $sender_rate_period
263 # Slow down fast senders
264 warn
265 ratelimit = 100 / 1h / per_rcpt / strict
266 delay = ${eval: 10 * ($sender_rate - $sender_rate_limit) }
268 # Keep authenticated users under control
269 deny
270 ratelimit = 100 / 1d / strict / $authenticated_id
272 # System-wide rate limit
273 defer
274 message = Sorry, too busy. Try again later.
275 ratelimit = 10 / 1s / $primary_hostname
277 # Restrict incoming rate from each host, with a default rate limit
278 # set using a macro and special cases looked up in a table.
279 defer
280 message = Sender rate $sender_rate exceeds \
281 $sender_rate_limit messages per $sender_rate_period
282 ratelimit = ${lookup {$sender_host_address} \
283 cdb {DB/ratelimits.cdb} \
284 {$value} {RATELIMIT} }
286 Warning: if you have a busy server with a lot of ratelimit tests,
287 especially with the per_rcpt option, you may suffer from a performance
288 bottleneck caused by locking on the ratelimit hints database. Apart from
289 making your ACLs less complicated, you can reduce the problem by using a
290 RAM disk for Exim's hints directory, /var/spool/exim/db/. However this
291 means that Exim will lose its hints data after a reboot (including retry
292 hints, the callout cache, and ratelimit data).
294TK/01 Added an 'spf' lookup type that will return an SPF result for a given
295 email address (the key) and an IP address (the database):
297 ${lookup {} spf{}}
299 The lookup will return the same result strings as they can appear in
300 $spf_result (pass,fail,softfail,neutral,none,err_perm,err_temp). The
301 lookup is armored in EXPERIMENTAL_SPF. Currently, only IPv4 addresses
302 are supported.
304 Patch submitted by Chris Webb <>.
306PH/02 There's a new verify callout option, "fullpostmaster", which first acts
307 as "postmaster" and checks the recipient <postmaster@domain>. If that
308 fails, it tries just <postmaster>, without a domain, in accordance with
309 the specification in RFC 2821.
311PH/03 The action of the auto_thaw option has been changed. It no longer applies
312 to frozen bounce messages.
314TK/02 There are two new expansion items to help with the implementation of
315 the BATV "prvs" scheme in an Exim configuration:
318 ${prvs {<ADDRESS>}{<KEY>}{[KEYNUM]}}
320 The "prvs" expansion item takes three arguments: A qualified RFC2821
321 email address, a key and an (optional) key number. All arguments are
322 expanded before being used, so it is easily possible to lookup a key
323 and key number using the address as the lookup key. The key number is
324 optional and defaults to "0". The item will expand to a "prvs"-signed
325 email address, to be typically used with the "return_path" option on
326 a smtp transport. The decision if BATV should be used with a given
327 sender/recipient pair should be done on router level, to avoid having
328 to set "max_rcpt = 1" on the transport.
331 ${prvscheck {<ADDRESS>}{<SECRET>}{<RETURN_STRING>}}
333 The "prvscheck" expansion item takes three arguments. Argument 1 is
334 expanded first. When the expansion does not yield a SYNTACTICALLY
335 valid "prvs"-scheme address, the whole "prvscheck" item expands to
336 the empty string. If <ADDRESS> is a "prvs"-encoded address after
337 expansion, two expansion variables are set up:
339 $prvscheck_address Contains the "prvs"-decoded version of
340 the address from argument 1.
342 $prvscheck_keynum Contains the key number extracted from
343 the "prvs"-address in argument 1.
345 These two variables can be used in the expansion code of argument 2
346 to retrieve the <SECRET>. The VALIDITY of the "prvs"-signed address
347 is then checked. The result is stored in yet another expansion
348 variable:
350 $prvscheck_result Contains the result of a "prvscheck"
351 expansion: Unset (the empty string) for
352 failure, "1" for success.
354 The "prvscheck" expansion expands to the empty string if <ADDRESS>
355 is not a SYNTACTICALLY valid "prvs"-scheme address. Otherwise,
356 argument 3 defines what "prvscheck" expands to: If argument 3
357 is the empty string, "prvscheck" expands to the decoded version
358 of the address (no matter if it is CRYPTOGRAPHICALLY valid or not).
359 If argument 3 expands to a non-empty string, "prvscheck" expands
360 to that string.
363 Usage example
364 -------------
366 Macro:
368 PRVSCHECK_SQL = ${lookup mysql{SELECT secret FROM batv_prvs WHERE \
369 sender='${quote_mysql:$prvscheck_address}'}{$value}}
373 # Bounces: drop unsigned addresses for BATV senders
374 deny message = This address does not send an unsigned reverse path.
375 senders = :
376 recipients = +batv_recipients
378 # Bounces: In case of prvs-signed address, check signature.
379 deny message = Invalid reverse path signature.
380 senders = :
381 condition = ${prvscheck {$local_part@$domain}{PRVSCHECK_SQL}{1}}
382 !condition = $prvscheck_result
384 Top-Level Router:
386 batv_redirect:
387 driver = redirect
388 data = ${prvscheck {$local_part@$domain}{PRVSCHECK_SQL}{}}
390 Transport (referenced by router that makes decision if
391 BATV is applicable):
393 external_smtp_batv:
394 driver = smtp
395 return_path = ${prvs {$return_path} \
396 {${lookup mysql{SELECT \
397 secret FROM batv_prvs WHERE \
398 sender='${quote_mysql:$sender_address}'} \
399 {$value}fail}}}
401PH/04 There are two new options that control the retrying done by the daemon
402 at startup when it cannot immediately bind a socket (typically because
403 the socket is already in use). The default values reproduce what were
404 built-in constants previously: daemon_startup_retries defines the number
405 of retries after the first failure (default 9); daemon_startup_sleep
406 defines the length of time to wait between retries (default 30s).
0cd68797 407
408PH/05 There is now a new ${if condition called "match_ip". It is similar to
409 match_domain, etc. It must be followed by two argument strings. The first
410 (after expansion) must be an IP address or an empty string. The second
411 (after expansion) is a restricted host list that can match only an IP
412 address, not a host name. For example:
414 ${if match_ip{$sender_host_address}{}{...}{...}}
416 The specific types of host list item that are permitted in the list are
417 shown below. Consult the manual section on host lists for further
418 details.
420 . An IP address, optionally with a CIDR mask.
422 . A single asterisk matches any IP address.
424 . An empty item matches only if the IP address is empty. This could be
425 useful for testing for a locally submitted message or one from specific
426 hosts in a single test such as
428 ${if match_ip{$sender_host_address}{:}{...}{...}}
430 where the first item in the list is the empty string.
432 . The item @[] matches any of the local host's interface addresses.
434 . Lookups are assumed to be "net-" style lookups, even if "net-" is not
435 specified. Thus, the following are equivalent:
437 ${if match_ip{$sender_host_address}{lsearch;/some/file}...
438 ${if match_ip{$sender_host_address}{net-lsearch;/some/file}...
440 You do need to specify the "net-" prefix if you want to specify a
441 specific address mask, for example, by using "net24-".
443PH/06 The "+all" debug selector used to set the flags for all possible output;
444 it is something that people tend to use semi-automatically when
445 generating debug output for me or for the list. However, by including
446 "+memory", an awful lot of output that is very rarely of interest was
447 generated. I have changed this so that "+all" no longer includes
448 "+memory". However, "-all" still turns everything off.
e5a9dba6 450
451Version 4.51
454PH/01 The format in which GnuTLS parameters are written to the gnutls-param
455 file in the spool directory has been changed. This change has been made
456 to alleviate problems that some people had with the generation of the
457 parameters by Exim when /dev/random was exhausted. In this situation,
458 Exim would hang until /dev/random acquired some more entropy.
460 The new code exports and imports the DH and RSA parameters in PEM
461 format. This means that the parameters can be generated externally using
462 the certtool command that is part of GnuTLS.
464 To replace the parameters with new ones, instead of deleting the file
465 and letting Exim re-create it, you can generate new parameters using
466 certtool and, when this has been done, replace Exim's cache file by
467 renaming. The relevant commands are something like this:
469 # rm -f new.params
470 # touch new.params
471 # chown exim:exim new.params
472 # chmod 0400 new.params
473 # certtool --generate-privkey --bits 512 >new.params
474 # echo "" >>new.params
475 # certtool --generate-dh-params --bits 1024 >> new.params
476 # mv new.params params
478 If Exim never has to generate the parameters itself, the possibility of
479 stalling is removed.
481PH/02 A new expansion item for dynamically loading and calling a locally-
482 written C function is now provided, if Exim is compiled with
486 set in Local/Makefile. The facility is not included by default (a
487 suitable error is given if you try to use it when it is not there.)
489 If you enable EXPAND_DLFUNC, you should also be aware of the new redirect
490 router option forbid_filter_dlfunc. If you have unprivileged users on
491 your system who are permitted to create filter files, you might want to
492 set forbid_filter_dlfunc=true in the appropriate router, to stop them
493 using ${dlfunc to run code within Exim.
495 You load and call an external function like this:
497 ${dlfunc{/some/file}{function}{arg1}{arg2}...}
499 Once loaded, Exim remembers the dynamically loaded object so that it
500 doesn't reload the same object file in the same Exim process (but of
501 course Exim does start new processes frequently).
503 There may be from zero to eight arguments to the function. When compiling
504 a local function that is to be called in this way, local_scan.h should be
505 included. The Exim variables and functions that are defined by that API
506 are also available for dynamically loaded functions. The function itself
507 must have the following type:
509 int dlfunction(uschar **yield, int argc, uschar *argv[])
511 Where "uschar" is a typedef for "unsigned char" in local_scan.h. The
512 function should return one of the following values:
514 OK Success. The string that is placed in "yield" is put into
515 the expanded string that is being built.
517 FAIL A non-forced expansion failure occurs, with the error
518 message taken from "yield", if it is set.
520 FAIL_FORCED A forced expansion failure occurs, with the error message
521 taken from "yield" if it is set.
523 ERROR Same as FAIL, except that a panic log entry is written.
525 When compiling a function that is to be used in this way with gcc,
526 you need to add -shared to the gcc command. Also, in the Exim build-time
527 configuration, you must add -export-dynamic to EXTRALIBS.
b5aea5e1 528
529TF/01 $received_time is a new expansion variable containing the time and date
530 as a number of seconds since the start of the Unix epoch when the
531 current message was received.
b5aea5e1 532
533PH/03 There is a new value for RADIUS_LIB_TYPE that can be set in
534 Local/Makefile. It is RADIUSCLIENTNEW, and it requests that the new API,
535 in use from radiusclient 0.4.0 onwards, be used. It does not appear to be
536 possible to detect the different versions automatically.
538PH/04 There is a new option called acl_not_smtp_mime that allows you to scan
539 MIME parts in non-SMTP messages. It operates in exactly the same way as
540 acl_smtp_mime
542PH/05 It is now possible to redefine a macro within the configuration file.
543 The macro must have been previously defined within the configuration (or
544 an included file). A definition on the command line using the -D option
545 causes all definitions and redefinitions within the file to be ignored.
546 In other words, -D overrides any values that are set in the file.
547 Redefinition is specified by using '==' instead of '='. For example:
549 MAC1 = initial value
550 ...
551 MAC1 == updated value
553 Redefinition does not alter the order in which the macros are applied to
554 the subsequent lines of the configuration file. It is still the same
555 order in which the macros were originally defined. All that changes is
556 the macro's value. Redefinition makes it possible to accumulate values.
557 For example:
559 MAC1 = initial value
560 ...
561 MAC1 == MAC1 and something added
563 This can be helpful in situations where the configuration file is built
564 from a number of other files.
566PH/06 Macros may now be defined or redefined between router, transport,
567 authenticator, or ACL definitions, as well as in the main part of the
568 configuration. They may not, however, be changed within an individual
569 driver or ACL, or in the local_scan, retry, or rewrite sections of the
570 configuration.
572PH/07 $acl_verify_message is now set immediately after the failure of a
573 verification in an ACL, and so is available in subsequent modifiers. In
574 particular, the message can be preserved by coding like this:
576 warn !verify = sender
577 set acl_m0 = $acl_verify_message
579 Previously, $acl_verify_message was set only while expanding "message"
580 and "log_message" when a very denied access.
582PH/08 The redirect router has two new options, sieve_useraddress and
583 sieve_subaddress. These are passed to a Sieve filter to specify the :user
584 and :subaddress parts of an address. Both options are unset by default.
585 However, when a Sieve filter is run, if sieve_useraddress is unset, the
586 entire original local part (including any prefix or suffix) is used for
587 :user. An unset subaddress is treated as an empty subaddress.
475fe28a 588
589PH/09 Quota values can be followed by G as well as K and M.
591PH/10 $message_linecount is a new variable that contains the total number of
592 lines in the header and body of the message. Compare $body_linecount,
593 which is the count for the body only. During the DATA and
594 content-scanning ACLs, $message_linecount contains the number of lines
595 received. Before delivery happens (that is, before filters, routers, and
596 transports run) the count is increased to include the Received: header
597 line that Exim standardly adds, and also any other header lines that are
598 added by ACLs. The blank line that separates the message header from the
599 body is not counted. Here is an example of the use of this variable in a
602 deny message = Too many lines in message header
603 condition = \
604 ${if <{250}{${eval: $message_linecount - $body_linecount}}}
606 In the MAIL and RCPT ACLs, the value is zero because at that stage the
607 message has not yet been received.
609PH/11 In a ${run expansion, the variable $value (which contains the standard
610 output) is now also usable in the "else" string.
612PH/12 In a pipe transport, although a timeout while waiting for the pipe
613 process to complete was treated as a delivery failure, a timeout while
614 writing the message to the pipe was logged, but erroneously treated as a
615 successful delivery. Such timeouts include transport filter timeouts. For
616 consistency with the overall process timeout, these timeouts are now
617 treated as errors, giving rise to delivery failures by default. However,
618 there is now a new Boolean option for the pipe transport called
619 timeout_defer, which, if set TRUE, converts the failures into defers for
620 both kinds of timeout. A transport filter timeout is now identified in
621 the log output.
7766a4f0 623
f7b63901 624Version 4.50
b9e40c51 627The documentation is up-to-date for the 4.50 release.