doc/doc-txt/NewStuff

   1 $Cambridge: exim/doc/doc-txt/NewStuff,v 1.20 2004/12/17 14:52:44 ph10 Exp $
   2
   3 New Features in Exim
   4 --------------------
   5
   6 This file contains descriptions of new features that have been added to Exim,
   7 but have not yet made it into the main manual (which is most conveniently
   8 updated when there is a relatively large batch of changes). The doc/ChangeLog
   9 file contains a listing of all changes, including bug fixes.
  10
  11
  12 Version 4.50
  13 ------------
  14
  15  1. There is a new build-time option called CONFIGURE_GROUP which works like
  16     CONFIGURE_OWNER. It specifies one additional group that is permitted for
  17     the runtime configuration file when the group write permission is set.
  18
  19  2. The "control=submission" facility has a new option /sender_retain. This
  20     has the effect of setting local_sender_retain true and local_from_check
  21     false for the incoming message in which it is encountered.
  22
  23  3. $recipients is now available in the predata ACL (oversight).
  24
  25  4. The value of address_data from a sender verification is now available in
  26     $sender_address_data in subsequent conditions in the ACL statement. Note:
  27     this is just like $address_data. The value does not persist after the end
  28     of the current ACL statement. If you want to preserve it, you can use one
  29     of the ACL variables.
  30
  31  5. The redirect router has two new options: forbid_sieve_filter and
  32     forbid_exim_filter. When filtering is enabled by allow_filter, these
  33     options control which type(s) of filtering are permitted. By default, both
  34     Exim and Sieve filters are allowed.
  35
  36  6. A new option for callouts makes it possible to set a different (usually
  37     smaller) timeout for making the SMTP connection. The keyword is "connect".
  38     For example:
  39
  40        verify = sender/callout=5s,connect=1s
  41
  42     If not specified, it defaults to the general timeout value.
  43
  44  7. The new variables $sender_verify_failure and $recipient_verify_failure
  45     contain information about exactly what failed. In an ACL, after one of
  46     these failures, the relevant variable contains one of the following words:
  47
  48       qualify       the address was unqualified (no domain), and the message
  49                     was neither local nor came from an exempted host;
  50
  51       route         routing failed;
  52
  53       mail          routing succeeded, and a callout was attempted; rejection
  54                     occurred at or before the MAIL command (that is, on initial
  55                     connection, HELO, or MAIL);
  56
  57       recipient     the RCPT command in a callout was rejected;
  58
  59       postmaster    the postmaster check in a callout was rejected.
  60
  61     The main use of these variables is expected to be to distinguish between
  62     rejections of MAIL and rejections of RCPT.
  63
  64  8. The command line option -dd behaves exactly like -d except when used on a
  65     command that starts a daemon process. In that case, debugging is turned off
  66     for the subprocesses that the daemon creates. Thus, it is useful for
  67     monitoring the behaviour of the daemon without creating as much output as
  68     full debugging.
  69
  70  9. $host_address is now set to the target address during the checking of
  71     ignore_target_hosts.
  72
  73 10. There are four new variables called $spool_space, $log_space,
  74     $spool_inodes, and $log_inodes. The first two contain the amount of free
  75     space in the disk partitions where Exim has its spool directory and log
  76     directory, respectively. (When these are in the same partition, the values
  77     will, of course, be the same.) The second two variables contain the numbers
  78     of free inodes in the respective partitions.
  79
  80     NOTE: Because disks can nowadays be very large, the values in the space
  81     variables are in kilobytes rather than in bytes. Thus, for example, to
  82     check in an ACL that there is at least 50M free on the spool, you would
  83     write:
  84
  85        condition = ${if > {$spool_space}{50000}{yes}{no}}
  86
  87     The values are recalculated whenever any of these variables is referenced.
  88     If the relevant file system does not have the concept of inodes, the value
  89     of those variables is -1. If the operating system does not have the ability
  90     to find the amount of free space (only true for experimental systems), the
  91     space value is -1.
  92
  93 11. It is now permitted to omit both strings after an "if" condition; if the
  94     condition is true, the result is the string "true". As before, when the
  95     second string is omitted, a false condition yields an empty string. This
  96     makes it less cumbersome to write custom ACL and router conditions. For
  97     example, instead of
  98
  99       condition = ${if eq {$acl_m4}{1}{yes}{no}}
 100
 101     or the shorter form
 102
 103       condition = ${if eq {$acl_m4}{1}{yes}}
 104
 105     (because the second string has always defaulted to ""), you can now write
 106
 107       condition = ${if eq {$acl_m4}{1}}
 108
 109     Previously this was a syntax error.
 110
 111 12. There is a new "record type" that can be specified in dnsdb lookups. It
 112     is "zns" (for "zone NS"). It performs a lookup for NS records on the given
 113     domain, but if none are found, it removes the first component of the domain
 114     name, and tries again. This process continues until NS records are found
 115     or there are no more components left (or there's a DNS error). In other
 116     words, it may return the name servers for a top-level domain, but it never
 117     returns the root name servers. If there are no NS records for the top-level
 118     domain, the lookup fails.
 119
 120     For example, ${lookup dnsdb{zns=xxx.quercite.com}} returns the name
 121     servers for quercite.com, whereas ${lookup dnsdb{zns=xxx.edu}} returns
 122     the name servers for edu, assuming in each case that there are no NS
 123     records for the full domain name.
 124
 125     You should be careful about how you use this lookup because, unless the
 126     top-level domain does not exist, the lookup will always return some host
 127     names. The sort of use to which this might be put is for seeing if the name
 128     servers for a given domain are on a blacklist. You can probably assume that
 129     the name servers for the high-level domains such as .com or .co.uk are not
 130     going to be on such a list.
 131
 132 13. Another new "record type" is "mxh"; this looks up MX records just as "mx"
 133     does, but it returns only the names of the hosts, omitting the priority
 134     values.
 135
 136 14. It is now possible to specify a list of domains or IP addresses to be
 137     looked up in a dnsdb lookup. The list is specified in the normal Exim way,
 138     with colon as the default separator, but with the ability to change this.
 139     For example:
 140
 141       ${lookup dnsdb{one.domain.com:two.domain.com}}
 142       ${lookup dnsdb{a=one.host.com:two.host.com}}
 143       ${lookup dnsdb{ptr = <; 1.2.3.4 ; 4.5.6.8}}
 144
 145     In order to retain backwards compatibility, there is one special case: if
 146     the lookup type is PTR and no change of separator is specified, Exim looks
 147     to see if the rest of the string is precisely one IPv6 address. In this
 148     case, it does not treat it as a list.
 149
 150     The data from each lookup is concatenated, with newline separators (by
 151     default - see 14 below), in the same way that multiple DNS records for a
 152     single item are handled.
 153
 154     The dnsdb lookup fails only if all the DNS lookups fail. If there is a
 155     temporary DNS error for any of them, the remaining lookups are still done,
 156     and only if none of them succeed does the dnsdb lookup defer. As long as at
 157     least one of the DNS lookups yields some data, the dnsdb lookup succeeds.
 158
 159 15. It is now possible to specify the character to be used as a separator when
 160     a dnsdb lookup returns data from more than one DNS record. The default is a
 161     newline. To specify a different character, put '>' followed by the new
 162     character at the start of the query. For example:
 163
 164       ${lookup dnsdb{>: a=h1.test.ex:h2.test.ex}}
 165       ${lookup dnsdb{>| mxh=<;m1.test.ex;m2.test.ex}}
 166
 167     It is permitted to specify a space as the separator character. Note that
 168     more than one DNS record can be found for a single lookup item; this
 169     feature is relevant even when you do not specify a list.
 170
 171     The same effect could be achieved by wrapping the lookup in ${tr...}; this
 172     feature is just a syntactic simplification.
 173
 174 16. It is now possible to supply a list of domains and/or IP addresses to be
 175     lookup up in a DNS blacklist. Previously, only a single domain name could
 176     be given, for example:
 177
 178       dnslists = black.list.tld/$sender_host_name
 179
 180     What follows the slash can now be a list. As with all lists, the default
 181     separator is a colon. However, because this is a sublist within the list of
 182     DNS blacklist domains, it is necessary either to double the separators like
 183     this:
 184
 185       dnslists = black.list.tld/name.1::name.2
 186
 187     or to change the separator character, like this:
 188
 189       dnslists = black.list.tld/<;name.1;name.2
 190
 191     If an item in the list is an IP address, it is inverted before the DNS
 192     blacklist domain is appended. If it is not an IP address, no inversion
 193     occurs. Consider this condition:
 194
 195        dnslists = black.list.tls/<;192.168.1.2;a.domain
 196
 197     The DNS lookups that occur are for
 198
 199        2.1.168.192.black.list.tld  and  a.domain.black.list.tld
 200
 201     Once a DNS record has been found (that matches a specific IP return
 202     address, if specified), no further lookups are done. If there is a
 203     temporary DNS error, the rest of the sublist of domains or IP addresses is
 204     tried. The dnslists item itself defers only if none of the other DNS
 205     lookups in this sublist succeeds. In other words, a successful lookup for
 206     any of the items in the sublist overrides a defer for a previous item.
 207
 208 17. The log selector queue_time_overall causes Exim to output the time spent on
 209     the queue as an addition to the "Completed" message. Like queue_time (which
 210     puts the queue time on individual delivery lines), the time is tagged with
 211     "QT=", and it is measured from the time that the message starts to be
 212     received, so it includes the reception time.
 213
 214 18. It is now possible to use both -bF and -bf on the same command, in order to
 215     test a system filter and a user filter in the same run. For example:
 216
 217       exim -bF /system/filter -bf /user/filter </test/message
 218
 219     This is helpful when the system filter adds header lines or sets filter
 220     variables that are used by the user filter.
 221
 222 19. The Exiscan patch is now merged into the main source. See src/EDITME for
 223     parameters for the build.
 224
 225
 226 Version 4.43
 227 ------------
 228
 229  1. There is a new Boolean global option called mua_wrapper, defaulting false.
 230     This causes Exim to run an a restricted mode, in order to provide a very
 231     specific service.
 232
 233     Background: On a personal computer, it is a common requirement for all
 234     email to be sent to a smarthost. There are plenty of MUAs that can be
 235     configured to operate that way, for all the popular operating systems.
 236     However, there are MUAs for Unix-like systems that cannot be so configured:
 237     they submit messages using the command line interface of
 238     /usr/sbin/sendmail. In addition, utility programs such as cron submit
 239     messages this way.
 240
 241     Requirement: The requirement is for something that can provide the
 242     /usr/sbin/sendmail interface and deliver messages to a smarthost, but not
 243     provide any queueing or retrying facilities. Furthermore, the delivery to
 244     the smarthost should be synchronous, so that if it fails, the sending MUA
 245     is immediately informed. In other words, we want something that in effect
 246     converts a command-line MUA into a TCP/SMTP MUA.
 247
 248     Solutions: There are a number of applications (for example, ssmtp) that do
 249     this job. However, people have found them to be lacking in various ways.
 250     For instance, some sites want to allow aliasing and forwarding before
 251     sending to the smarthost.
 252
 253     Using Exim: Exim already had the necessary infrastructure for doing this
 254     job. Just a few tweaks were needed to make it behave as required, though it
 255     is somewhat of an overkill to use a fully-featured MTA for this purpose.
 256
 257     Setting mua_wrapper=true causes Exim to run in a special mode where it
 258     assumes that it is being used to "wrap" a command-line MUA in the manner
 259     just described.
 260
 261     If you set mua_wrapper=true, you also need to provide a compatible router
 262     and transport configuration. Typically there will be just one router and
 263     one transport, sending everything to a smarthost.
 264
 265     When run in MUA wrapping mode, the behaviour of Exim changes in the
 266     following ways:
 267
 268     (a) A daemon cannot be run, nor will Exim accept incoming messages from
 269         inetd. In other words, the only way to submit messages is via the
 270         command line.
 271
 272     (b) Each message is synchonously delivered as soon as it is received (-odi
 273         is assumed). All queueing options (queue_only, queue_smtp_domains,
 274         control=queue, control=freeze in an ACL etc.) are quietly ignored. The
 275         Exim reception process does not finish until the delivery attempt is
 276         complete. If the delivery was successful, a zero return code is given.
 277
 278     (c) Address redirection is permitted, but the final routing for all
 279         addresses must be to the same remote transport, and to the same list of
 280         hosts. Furthermore, the return_address must be the same for all
 281         recipients, as must any added or deleted header lines. In other words,
 282         it must be possible to deliver the message in a single SMTP
 283         transaction, however many recipients there are.
 284
 285     (d) If the conditions in (c) are not met, or if routing any address results
 286         in a failure or defer status, or if Exim is unable to deliver all the
 287         recipients successfully to one of the hosts immediately, delivery of
 288         the entire message fails.
 289
 290     (e) Because no queueing is allowed, all failures are treated as permanent;
 291         there is no distinction between 4xx and 5xx SMTP response codes from
 292         the smarthost. Furthermore, because only a single yes/no response can
 293         be given to the caller, it is not possible to deliver to some
 294         recipients and not others. If there is an error (temporary or
 295         permanent) for any recipient, all are failed.
 296
 297     (f) If more than one host is listed, Exim will try another host after a
 298         connection failure or a timeout, in the normal way. However, if this
 299         kind of failure happens for all the hosts, the delivery fails.
 300
 301     (g) When delivery fails, an error message is written to the standard error
 302         stream (as well as to Exim's log), and Exim exits to the caller with a
 303         return code value 1. The message is expunged from Exim's spool files.
 304         No bounce messages are ever generated.
 305
 306     (h) No retry data is maintained, and any retry rules are ignored.
 307
 308     (i) A number of Exim options are overridden: deliver_drop_privilege is
 309         forced true, max_rcpt in the smtp transport is forced to "unlimited",
 310         remote_max_parallel is forced to one, and fallback hosts are ignored.
 311
 312     The overall effect is that Exim makes a single synchronous attempt to
 313     deliver the message, failing if there is any kind of problem. Because no
 314     local deliveries are done and no daemon can be run, Exim does not need root
 315     privilege. It should be possible to run it setuid=exim instead of
 316     setuid=root. See section 48.3 in the 4.40 manual for a general discussion
 317     about the advantages and disadvantages of running without root privilege.
 318
 319  2. There have been problems with DNS servers when SRV records are looked up.
 320     Some mis-behaving servers return a DNS error or timeout when a non-existent
 321     SRV record is sought. Similar problems have in the past been reported for
 322     MX records. The global dns_again_means_nonexist option can help with this
 323     problem, but it is heavy-handed because it is a global option. There are
 324     now two new options for the dnslookup router. They are called
 325     srv_fail_domains and mx_fail_domains. In each case, the value is a domain
 326     list. If an attempt to look up an SRV or MX record results in a DNS failure
 327     or "try again" response, and the domain matches the relevant list, Exim
 328     behaves as if the DNS had responded "no such record". In the case of an SRV
 329     lookup, this means that the router proceeds to look for MX records; in the
 330     case of an MX lookup, it proceeds to look for A or AAAA records, unless the
 331     domain matches mx_domains.
 332
 333  3. The following functions are now available in the local_scan() API:
 334
 335     (a) void header_remove(int occurrence, uschar *name)
 336
 337         This function removes header lines. If "occurrence" is zero or negative,
 338         all occurrences of the header are removed. If occurrence is greater
 339         than zero, that particular instance of the header is removed. If no
 340         header(s) can be found that match the specification, the function does
 341         nothing.
 342
 343     (b) BOOL header_testname(header_line *hdr, uschar *name, int length,
 344                              BOOL notdel)
 345
 346         This function tests whether the given header has the given name. It
 347         is not just a string comparison, because whitespace is permitted
 348         between the name and the colon. If the "notdel" argument is TRUE, a
 349         FALSE return is forced for all "deleted" headers; otherwise they are
 350         not treated specially. For example:
 351
 352            if (header_testname(h, US"X-Spam", 6, TRUE)) ...
 353
 354     (c) void header_add_at_position(BOOL after, uschar *name, BOOL topnot,
 355                                     int type, char *format, ...)
 356
 357         This function adds a new header line at a specified point in the header
 358         chain. If "name" is NULL, the new header is added at the end of the
 359         chain if "after" is TRUE, or at the start if "after" is FALSE. If
 360         "name" is not NULL, the headers are searched for the first non-deleted
 361         header that matches the name. If one is found, the new header is added
 362         before it if "after" is FALSE. If "after" is true, the new header is
 363         added after the found header and any adjacent subsequent ones with the
 364         same name (even if marked "deleted"). If no matching non-deleted header
 365         is found, the "topnot" option controls where the header is added. If it
 366         is TRUE, addition is at the top; otherwise at the bottom. Thus, to add
 367         a header after all the Received: headers, or at the top if there are no
 368         Received: headers, you could use
 369
 370           header_add_at_position(TRUE, US"Received", TRUE, ' ', "X-xxx: ...");
 371
 372         Normally, there is always at least one non-deleted Received: header,
 373         but there may not be if received_header_text expands to an empty
 374         string.
 375
 376     (d) BOOL receive_remove_recipient(uschar *recipient)
 377
 378         This is a convenience function to remove a named recipient from the
 379         list of recipients. It returns TRUE if a recipient was removed, and
 380         FALSE if no matching recipient could be found. The argument must be a
 381         complete email address.
 382
 383  4. When an ACL "warn" statement adds one or more header lines to a message,
 384     they are added at the end of the existing header lines by default. It is
 385     now possible to specify that any particular header line should be added
 386     right at the start (before all the Received: lines) or immediately after
 387     the first block of Received: lines in the message. This is done by
 388     specifying :at_start: or :after_received: (or, for completeness, :at_end:)
 389     before the text of the header line. (Header text cannot start with a colon,
 390     as there has to be a header name first.) For example:
 391
 392       warn message = :after_received:X-My-Header: something or other...
 393
 394     If more than one header is supplied in a single warn statement, each one is
 395     treated independently and can therefore be placed differently. If you add
 396     more than one line at the start, or after the Received: block, they will
 397     end up in reverse order.
 398
 399     Warning: This facility currently applies only to header lines that are
 400     added in an ACL. It does NOT work for header lines that are added in a
 401     system filter or in a router or transport.
 402
 403  5. There is now a new error code that can be used in retry rules. Its name is
 404     "rcpt_4xx", and there are three forms. A literal "rcpt_4xx" matches any 4xx
 405     error received for an outgoing SMTP RCPT command; alternatively, either the
 406     first or both of the x's can be given as digits, for example: "rcpt_45x" or
 407     "rcpt_436". If you want (say) to recognize 452 errors given to RCPT
 408     commands by a particular host, and have only a one-hour retry for them, you
 409     can set up a retry rule of this form:
 410
 411       the.host.name  rcpt_452   F,1h,10m
 412
 413     Naturally, this rule must come before any others that would match.
 414
 415     These new errors apply to both outgoing SMTP (the smtp transport) and
 416     outgoing LMTP (either the lmtp transport, or the smtp transport in LMTP
 417     mode). Note, however, that they apply only to responses to RCPT commands.
 418
 419  6. The "postmaster" option of the callout feature of address verification has
 420     been extended to make it possible to use a non-empty MAIL FROM address when
 421     checking a postmaster address. The new suboption is called "postmaster_
 422     mailfrom", and you use it like this:
 423
 424       require  verify = sender/callout=postmaster_mailfrom=abc@x.y.z
 425
 426     Providing this suboption causes the postmaster check to be done using the
 427     given address. The original "postmaster" option is equivalent to
 428
 429       require  verify = sender/callout=postmaster_mailfrom=
 430
 431     If both suboptions are present, the rightmost one overrides.
 432
 433     Important notes:
 434
 435     (1) If you use a non-empty sender address for postmaster checking, there is
 436         the likelihood that the remote host will itself initiate a callout
 437         check back to your host to check that address. As this is a "normal"
 438         callout check, the sender will most probably be empty, thus avoiding
 439         possible callout loops. However, to be on the safe side it would be
 440         best to set up your own ACLs so that they do not do sender verification
 441         checks when the recipient is the address you use for postmaster callout
 442         checking.
 443
 444     (2) The caching arrangements for postmaster checking do NOT take account of
 445         the sender address. It is assumed that either the empty address, or a
 446         fixed non-empty address will be used. All that Exim remembers is that
 447         the postmaster check for the domain succeeded or failed.
 448
 449  7. When verifying addresses in header lines using the verify=header_sender
 450     option, Exim behaves by default as if the addresses are envelope sender
 451     addresses from a message. Callout verification therefore tests to see
 452     whether a bounce message could be delivered, by using an empty address in
 453     the MAIL FROM command. However, it is arguable that these addresses might
 454     never be used as envelope senders, and could therefore justifiably reject
 455     bounce messages (empty senders). There is now an additional callout option
 456     for verify=header_sender that allows you to specify what address to use in
 457     the MAIL FROM command. You use it as in this example:
 458
 459       require  verify = header_sender/callout=mailfrom=abcd@x.y.z
 460
 461     Important notes:
 462
 463     (1) As in the case of postmaster_mailfrom (see above), you should think
 464         about possible loops.
 465
 466     (2) In this case, as in the case of recipient callouts with non-empty
 467         senders (the use_sender option), caching is done on the basis of a
 468         recipient/sender pair.
 469
 470  8. If you build Exim with USE_READLINE=yes in Local/Makefile, it will try to
 471     load libreadline dynamically whenever the -be (test expansion) option is
 472     used without command line arguments. If successful, it will then use
 473     readline() for reading the test data. A line history is supported. By the
 474     time Exim does this, it is running as the calling user, so this should not
 475     cause any security problems. Security is the reason why this is NOT
 476     supported for -bt or -bv, when Exim is running as root or exim,
 477     respectively. Note that this option adds to the size of the Exim binary,
 478     because the dynamic loading library is not otherwise included. On my
 479     desktop it adds about 2.5K. You may need to add -ldl to EXTRA_LIBS when you
 480     set USE_READLINE=yes.
 481
 482  9. Added ${str2b64:<string>} to the expansion operators. This operator
 483     converts an arbitrary string into one that is base64 encoded.
 484
 485 10. A new authenticator, called cyrus_sasl, has been added. This requires
 486     the presence of the Cyrus SASL library; it authenticates by calling this
 487     library, which supports a number of authentication mechanisms, including
 488     PLAIN and LOGIN, but also several others that Exim does not support
 489     directly. The code for this authenticator was provided by Matthew
 490     Byng-Maddick of A L Digital Ltd (http://www.aldigital.co.uk). Here follows
 491     draft documentation:
 492
 493                     xx. THE CYRUS_SASL AUTHENTICATOR
 494
 495     The cyrus_sasl authenticator provides server support for the Cyrus library
 496     Implementation of the RFC 2222 "Simple Authentication and Security Layer".
 497     It provides a gatewaying mechanism directly to the Cyrus interface, so if
 498     your Cyrus library can do, for example, CRAM-MD5, then so can the
 499     cyrus_sasl authenticator. By default it uses the public name of the driver
 500     to determine which mechanism to support.
 501
 502     Where access to some kind of secret file is required, for example in GSSAPI
 503     or CRAM-MD5, it is worth noting that the authenticator runs as the exim
 504     user, and that the Cyrus SASL library has no way of escalating privileges
 505     by default. You may also find you need to set environment variables,
 506     depending on the driver you are using.
 507
 508     xx.1 Using cyrus_sasl as a server
 509
 510     The cyrus_sasl authenticator has four private options. It puts the username
 511     (on a successful authentication) into $1.
 512
 513     server_hostname         Type: string*         Default: $primary_hostname
 514
 515         This option selects the hostname that is used when communicating with
 516         the library. It is up to the underlying SASL plug-in what it does with
 517         this data.
 518
 519     server_mech             Type: string                Default: public_name
 520
 521         This option selects the authentication mechanism this driver should
 522         use. It allows you to use a different underlying mechanism from the
 523         advertised name. For example:
 524
 525         sasl:
 526           driver = cyrus_sasl
 527           public_name = X-ANYTHING
 528           server_mech = CRAM-MD5
 529           server_set_id = $1
 530
 531     server_realm            Type: string                      Default: unset
 532
 533        This is the SASL realm that the server is claiming to be in.
 534
 535     server_service          Type: string                      Default: "smtp"
 536
 537        This is the SASL service that the server claims to implement.
 538
 539     For straigthforward cases, you do not need to set any of the
 540     authenticator's private options. All you need to do is to specify an
 541     appropriate mechanism as the public name. Thus, if you have a SASL library
 542     that supports CRAM-MD5 and PLAIN, you might have two authenticators as
 543     follows:
 544
 545       sasl_cram_md5:
 546         driver = cyrus_sasl
 547         public_name = CRAM-MD5
 548         server_set_id = $1
 549
 550       sasl_plain:
 551         driver = cyrus_sasl
 552         public_name = PLAIN
 553         server_set_id = $1
 554
 555 11. There is a new global option called tls_on_connect_ports. Its value must be
 556     a list of port numbers; the most common use is expected to be
 557
 558       tls_on_connect_ports = 465
 559
 560     Setting this option has the same effect as -tls-on-connect on the command
 561     line, but only for the specified ports. It applies to all connections, both
 562     via the daemon and via inetd. You still need to specify all the ports for
 563     the daemon (using daemon_smtp_ports or local_interfaces or the -X command
 564     line option) because this option does not add an extra port -- rather, it
 565     specifies different behaviour on a port that is defined elsewhere. The
 566     -tls-on-connect command line option overrides tls_on_connect_ports, and
 567     forces tls-on-connect for all ports.
 568
 569 12. There is a new ACL that is run when a DATA command is received, before the
 570     data itself is received. The ACL is defined by acl_smtp_predata. (Compare
 571     acl_smtp_data, which is run after the data has been received.)
 572     This new ACL allows a negative response to be given to the DATA command
 573     itself. Header lines added by MAIL or RCPT ACLs are not visible at this
 574     time, but any that are defined here are visible when the acl_smtp_data ACL
 575     is run.
 576
 577 13. The "control=submission" ACL modifier has an option "/domain=xxx" which
 578     specifies the domain to be used when creating From: or Sender: lines using
 579     the authenticated id as a local part. If the option is supplied with an
 580     empty domain, that is, just "/domain=", Exim assumes that the authenticated
 581     id is a complete email address, and it uses it as is when creating From:
 582     or Sender: lines.
 583
 584 14. It is now possible to make retry rules that apply only when the failing
 585     message has a specific sender. In particular, this can be used to define
 586     retry rules that apply only to bounce messages. The syntax is to add a new
 587     third item to a retry rule, of the form "senders=<address list>". The retry
 588     timings themselves then become the fourth item. For example:
 589
 590       *   *   senders=:   F,1h,30m
 591
 592     would match all bounce messages. If the address list contains white space,
 593     it must be enclosed in quotes. For example:
 594
 595       a.domain  timeout  senders="x@b.dom : y@c.dom"  G,8h,10m,1.5
 596
 597     When testing retry rules using -brt, you can supply a sender using the -f
 598     command line option, like this:
 599
 600       exim -f "" -brt user@dom.ain
 601
 602     If you do not set -f with -brt, a retry rule that contains a senders list
 603     will never be matched.
 604
 605 15. Two new control modifiers have been added to ACLs: "control = enforce_sync"
 606     and "control = no_enforce_sync". This makes it possible to be selective
 607     about when SMTP synchronization is enforced. The global option
 608     smtp_enforce_sync now specifies the default state of the switch. These
 609     controls can appear in any ACL, but the most obvious place to put them is
 610     in the ACL defined by acl_smtp_connect, which is run at the start of an
 611     incoming SMTP connection, before the first synchronization check.
 612
 613 16. Another two new control modifiers are "control = caseful_local_part" and
 614     "control = caselower_local_part". These are permitted only in the ACL
 615     specified by acl_smtp_rcpt (i.e. during RCPT processing). By default, the
 616     contents of $local_part are lower cased before ACL processing.
 617     After "control = caseful_local_part", any uppercase letters in the original
 618     local part are restored in $local_part for the rest of the ACL, or until
 619     "control = caselower_local_part" is encountered. However, this applies only
 620     to local part handling that takes place directly in the ACL (for example,
 621     as a key in lookups). If a "verify = recipient" test is obeyed, the
 622     case-related handling of the local part during the verification is
 623     controlled by the router configuration (see the caseful_local_part generic
 624     router option).
 625
 626     This facility could be used, for example, to add a spam score to local
 627     parts containing upper case letters. For example, using $acl_m4 to
 628     accumulate the spam score:
 629
 630       warn  control = caseful_local_part
 631             set acl_m4 = ${eval:\
 632                            $acl_m4 + \
 633                            ${if match{$local_part}{[A-Z]}{1}{0}}\
 634                           }
 635             control = caselower_local_part
 636
 637     Notice that we put back the lower cased version afterwards, assuming that
 638     is what is wanted for subsequent tests.
 639
 640 17. The option hosts_connection_nolog is provided so that certain hosts can be
 641     excepted from logging when the +smtp_connection log selector is set. For
 642     example, you might want not to log SMTP connections from local processes,
 643     or from 127.0.0.1, or from your local LAN. The option is a host list with
 644     an unset default. Because it is consulted in the main loop of the daemon,
 645     you should strive to restrict its value to a short inline list of IP
 646     addresses and networks. To disable logging SMTP connections from local
 647     processes, you must create a host list with an empty item. For example:
 648
 649       hosts_connection_nolog = :
 650
 651     If the +smtp_connection log selector is not set, this option has no effect.
 652
 653 18. There is now an acl called acl_smtp_quit, which is run for the QUIT
 654     command. The outcome of the ACL does not affect the response code to QUIT,
 655     which is always 221. Thus, the ACL does not in fact control any access.
 656     For this reason, the only verbs that are permitted are "accept" and "warn".
 657
 658     The ACL can be used for tasks such as custom logging at the end of an SMTP
 659     session. For example, you can use ACL variables in other ACLs to count
 660     messages, recipients, etc., and log the totals at QUIT time using one or
 661     more "logwrite" modifiers on a "warn" command.
 662
 663     You do not need to have a final "accept", but if you do, you can use a
 664     "message" modifier to specify custom text that is sent as part of the 221
 665     response.
 666
 667     This ACL is run only for a "normal" QUIT. For certain kinds of disastrous
 668     failure (for example, failure to open a log file, or when Exim is bombing
 669     out because it has detected an unrecoverable error), all SMTP commands
 670     from the client are given temporary error responses until QUIT is received
 671     or the connection is closed. In these special cases, the ACL is not run.
 672
 673 19. The appendfile transport has two new options, mailbox_size and mailbox_
 674     filecount. If either these options are set, it is expanded, and the result
 675     is taken as the current size of the mailbox or the number of files in the
 676     mailbox, respectively. This makes it possible to use some external means of
 677     maintaining the data about the size of a mailbox for enforcing quota
 678     limits. The result of expanding these option values must be a decimal
 679     number, optionally followed by "K" or "M".
 680
 681 20. It seems that there are broken clients in use that cannot handle multiline
 682     SMTP responses. Can't people who implement these braindead programs read?
 683     RFC 821 mentions multiline responses, and it is over 20 years old. They
 684     must handle multiline responses for EHLO, or do they still use HELO?
 685     Anyway, here is YAWFAB (yet another workaround for asinine brokenness).
 686     There's a new ACL switch that can be set by
 687
 688       control = no_multiline_responses
 689
 690     If this is set, it suppresses multiline SMTP responses from ACL rejections.
 691     One way of doing this would have been just to put out these responses as
 692     one long line. However, RFC 2821 specifies a maximum of 512 bytes per
 693     response ("use multiline responses for more" it says), and some of the
 694     responses might get close to that. So I have implemented this by doing two
 695     very easy things:
 696
 697       (1) Extra information that is normally output as part of a rejection
 698           caused by sender verification failure is omitted. Only the final line
 699           (typically "sender verification failed") is now sent.
 700
 701       (2) If a "message" modifier supplies a multiline response, only the first
 702           line is output.
 703
 704     The setting of the switch can, of course, be made conditional on the
 705     calling host.
 706
 707 21. There is now support for the libradius library that comes with FreeBSD.
 708     This is an alternative to the radiusclient library that Exim already
 709     supports. To use the FreeBSD library, you need to set
 710
 711       RADIUS_LIB_TYPE=RADLIB
 712
 713     in Local/Makefile, in addition to RADIUS_CONFIGURE_FILE, and you probably
 714     also need -libradius in EXTRALIBS.
 715
 716
 717 Version 4.42
 718 ------------
 719
 720  1. The "personal" filter test is brought up-to-date with recommendations from
 721     the Sieve specification: (a) The list of non-personal From: addresses now
 722     includes "listserv", "majordomo", and "*-request"; (b) If the message
 723     contains any header line starting with "List=-" it is treated as
 724     non-personal.
 725
 726  2. The Sieve functionality has been extended to support the "copy" and
 727     "vacation" extensions, and comparison tests.
 728
 729  3. There is now an overall timeout for performing a callout verification. It
 730     defaults to 4 times the callout timeout, which applies to individual SMTP
 731     commands during the callout. The overall timeout applies when there is more
 732     than one host that can be tried. The timeout is checked before trying the
 733     next host. This prevents very long delays if there are a large number of
 734     hosts and all are timing out (e.g. when the network connections are timing
 735     out). The value of the overall timeout can be changed by specifying an
 736     additional sub-option for "callout", called "maxwait". For example:
 737
 738       verify = sender/callout=5s,maxwait=20s
 739
 740  4. Changes to the "personal" filter test:
 741
 742     (1) The list of non-personal local parts in From: addresses has been
 743     extended to include "listserv", "majordomo", "*-request", and "owner-*",
 744     taken from the Sieve specification recommendations.
 745
 746     (2) If the message contains any header line starting with "List-" it is
 747     treated as non-personal.
 748
 749     (3) The test for "circular" in the Subject: header line has been removed
 750     because it now seems ill-conceived.
 751
 752  5. The autoreply transport has a new option called never_mail. This is an
 753     address list. If any run of the transport creates a message with a
 754     recipient that matches any item in the list, that recipient is quietly
 755     discarded. If all recipients are discarded, no message is created.
 756
 757
 758 Version 4.40
 759 ------------
 760
 761 The documentation is up-to-date for the 4.40 release. What follows here is a
 762 brief list of the new features that have been added since 4.30.
 763
 764  1. log_incoming_interface affects more log lines.
 765
 766  2. New ACL modifier "control = submission".
 767
 768  3. CONFIGURE_OWNER can be set at build time to define an alternative owner for
 769     the configuration file, in addition to root and exim.
 770
 771  4. Added expansion variables $body_zerocount, $recipient_data, and
 772     $sender_data.
 773
 774  5. The time of last modification of the "new" subdirectory is now used as the
 775     "mailbox time last read" when there is a quota error for a maildir
 776     delivery.
 777
 778  6. The special item "+ignore_unknown" may now appear in host lists.
 779
 780  7. The special domain-matching patterns @mx_any, @mx_primary, and
 781     @mx_secondary can now be followed by "/ignore=<ip list>".
 782
 783  8. New expansion conditions: match_domain, match_address, match_local_part,
 784     lt, lti, le, lei, gt, gti, ge, and new expansion operators time_interval,
 785     eval10, and base62d.
 786
 787  9. New lookup type called "iplsearch".
 788
 789 10. New log selectors ident_timeout, tls_certificate_verified, queue_time,
 790     deliver_time, outgoing_port, return_path_on_delivery.
 791
 792 11. New global options smtp_active_hostname and tls_require_ciphers.
 793
 794 12. Exinext has -C and -D options.
 795
 796 13. "domainlist_cache" forces caching of an apparently variable list.
 797
 798 14. For compatibility with Sendmail, the command line option -prval:sval
 799     is equivalent to -oMr rval -oMs sval.
 800
 801 15. New callout options use_sender and use_postmaster for use when verifying
 802     recipients.
 803
 804 16. John Jetmore's "exipick" utility has been added to the distribution.
 805
 806 17. The TLS code now supports CRLs.
 807
 808 18. The dnslookup router and the dnsdb lookup type now support the use of SRV
 809     records.
 810
 811 19. The redirect router has a new option called qualify_domain.
 812
 813 20. exigrep's output now also includes lines that are not related to any
 814     particular message, but which do match the pattern.
 815
 816 21. New global option write_rejectlog. If it is set false, Exim no longer
 817     writes anything to the reject log.
 818
 819 ****