-$Cambridge: exim/doc/doc-txt/NewStuff,v 1.120 2006/11/06 15:50:12 ph10 Exp $
+$Cambridge: exim/doc/doc-txt/NewStuff,v 1.123 2006/11/14 16:40:36 ph10 Exp $
New Features in Exim
--------------------
Version 4.64
------------
-1. ACL variables can now be given arbitrary names, as long as they start with
- "acl_c" or "acl_m" (for connection variables and message variables), are
- at least six characters long, with the sixth character being either a digit
- or an underscore. The rest of the name can contain alphanumeric characters
- and underscores. This is a compatible change because the old set of
- variables such as acl_m12 are a subset of the allowed names. There may now
- be any number of ACL variables. For example:
-
- set acl_c13 = value for original ACL variable
- set acl_c13b = whatever
- set acl_m_foo = something
-
- What happens if a syntactically valid but undefined ACL variable is
- referenced depends on the setting of the strict_acl_vars option. If it is
- false (the default), an empty string is substituted; if it is true, an error
- is generated. This affects all ACL variables, including the "old" ones such
- as acl_c4. (Previously there wasn't the concept of an undefined ACL
- variable.)
-
- The implementation has been done in such a way that spool files containing
- ACL variable settings written by previous releases of Exim are compatible
- and can be read by the new release. If only the original numeric names are
- used, spool files written by the new release can be read by earlier
- releases.
-
-2. There is a new ACL modifier called log_reject_target. It makes it possible
- to specify which logs are used for messages about ACL rejections. Its
- argument is a list of words which can be "main", "reject", or "panic". The
- default is "main:reject". The list may be empty, in which case a rejection
- is not logged at all. For example, this ACL fragment writes no logging
- information when access is denied:
-
- deny <some conditions>
- log_reject_target =
-
- The modifier can be used in SMTP and non-SMTP ACLs. It applies to both
- permanent and temporary rejections.
-
-3. There is a new authenticator called "dovecot". This is an interface to the
- authentication facility of the Dovecot POP/IMAP server, which can support a
- number of authentication methods. If you are using Dovecot to authenticate
- POP/IMAP clients, it might be helpful to use the same mechanisms for SMTP
- authentication. This is a server authenticator only. The only option is
- server_socket, which must specify the socket which is the interface to
- Dovecot authentication. The public_name option must specify an
- authentication mechanism that Dovecot is configured to support. You can have
- several authenticators for different mechanisms. For example:
-
- dovecot_plain:
- driver = dovecot
- public_name = PLAIN
- server_name = /var/run/dovecot/auth-client
- server_setid = $auth1
-
- dovecot_ntlm:
- driver = dovecot
- public_name = NTLM
- server_name = /var/run/dovecot/auth-client
- server_setid = $auth1
-
- If the SMTP connection is encrypted, or if $sender_host_address is equal to
- $interface_address (that is, the connection is local), the "secured" option
- is passed in the Dovecot authentication command. If, for a TLS connection, a
- client certificate has been verified, the "valid-client-cert" option is
- passed.
-
-4. The variable $message_headers_raw provides a concatenation of all the
- messages's headers without any decoding. This is in contrast to
- $message_headers, which does RFC2047 decoding on the header contents.
-
-5. In a DNS black list, when the facility for restricting the matching IP
- values is used, the text from the TXT record that is set in $dnslist_text
- may not reflect the true reason for rejection. This happens when lists are
- merged and the IP address in the A record is used to distinguish them;
- unfortunately there is only one TXT record. One way round this is not to use
- merged lists, but that can be inefficient because it requires multiple DNS
- lookups where one would do in the vast majority of cases when the host of
- interest is not on any of the lists.
-
- A less inefficient way of solving this problem has now been implemented. If
- two domain names, comma-separated, are given, the second is used first to do
- an initial check, making use of any IP value restrictions that are set. If
- there is a match, the first domain is used, without any IP value
- restrictions, to get the TXT record. As a byproduct of this, there is also a
- check that the IP being tested is indeed on the first list. The first domain
- is the one that is put in $dnslist_domain. For example:
-
- reject message = rejected because $sender_ip_address is blacklisted \
- at $dnslist_domain\n$dnslist_text
- dnslists = sbl.spamhaus.org,sbl-xbl.spamhaus.org=127.0.0.2 : \
- dul.dnsbl.sorbs.net,dnsbl.sorbs.net=127.0.0.10
-
- For the first blacklist item, this starts by doing a lookup in
- sbl-xbl.spamhaus.org and testing for a 127.0.0.2 return. If there is a
- match, it then looks in sbl.spamhaus.org, without checking the return value,
- and as long as something is found, it looks for the corresponding TXT
- record. If there is no match in sbl-xbl.spamhaus.org, nothing more is done.
- The second blacklist item is processed similarly.
-
- If you are interested in more than one merged list, the same list must be
- given several times, but because the results of the DNS lookups are cached,
- the DNS calls themselves are not repeated. For example:
-
- reject dnslists = http.dnsbl.sorbs.net,dnsbl.sorbs.net=127.0.0.2 : \
- socks.dnsbl.sorbs.net,dnsbl.sorbs.net=127.0.0.3 : \
- misc.dnsbl.sorbs.net,dnsbl.sorbs.net=127.0.0.4 : \
+ 1. ACL variables can now be given arbitrary names, as long as they start with
+ "acl_c" or "acl_m" (for connection variables and message variables), are at
+ least six characters long, with the sixth character being either a digit or
+ an underscore. The rest of the name can contain alphanumeric characters and
+ underscores. This is a compatible change because the old set of variables
+ such as acl_m12 are a subset of the allowed names. There may now be any
+ number of ACL variables. For example:
+
+ set acl_c13 = value for original ACL variable
+ set acl_c13b = whatever
+ set acl_m_foo = something
+
+ What happens if a syntactically valid but undefined ACL variable is
+ referenced depends on the setting of the strict_acl_vars option. If it is
+ false (the default), an empty string is substituted; if it is true, an
+ error is generated. This affects all ACL variables, including the "old"
+ ones such as acl_c4. (Previously there wasn't the concept of an undefined
+ ACL variable.)
+
+ The implementation has been done in such a way that spool files containing
+ ACL variable settings written by previous releases of Exim are compatible
+ and can be read by the new release. If only the original numeric names are
+ used, spool files written by the new release can be read by earlier
+ releases.
+
+ 2. There is a new ACL modifier called log_reject_target. It makes it possible
+ to specify which logs are used for messages about ACL rejections. Its
+ argument is a list of words which can be "main", "reject", or "panic". The
+ default is "main:reject". The list may be empty, in which case a rejection
+ is not logged at all. For example, this ACL fragment writes no logging
+ information when access is denied:
+
+ deny <some conditions>
+ log_reject_target =
+
+ The modifier can be used in SMTP and non-SMTP ACLs. It applies to both
+ permanent and temporary rejections.
+
+ 3. There is a new authenticator called "dovecot". This is an interface to the
+ authentication facility of the Dovecot POP/IMAP server, which can support a
+ number of authentication methods. If you are using Dovecot to authenticate
+ POP/IMAP clients, it might be helpful to use the same mechanisms for SMTP
+ authentication. This is a server authenticator only. The only option is
+ server_socket, which must specify the socket which is the interface to
+ Dovecot authentication. The public_name option must specify an
+ authentication mechanism that Dovecot is configured to support. You can
+ have several authenticators for different mechanisms. For example:
+
+ dovecot_plain:
+ driver = dovecot
+ public_name = PLAIN
+ server_name = /var/run/dovecot/auth-client
+ server_setid = $auth1
+
+ dovecot_ntlm:
+ driver = dovecot
+ public_name = NTLM
+ server_name = /var/run/dovecot/auth-client
+ server_setid = $auth1
+
+ If the SMTP connection is encrypted, or if $sender_host_address is equal to
+ $interface_address (that is, the connection is local), the "secured" option
+ is passed in the Dovecot authentication command. If, for a TLS connection,
+ a client certificate has been verified, the "valid-client-cert" option is
+ passed.
+
+ 4. The variable $message_headers_raw provides a concatenation of all the
+ messages's headers without any decoding. This is in contrast to
+ $message_headers, which does RFC2047 decoding on the header contents.
+
+ 5. In a DNS black list, when the facility for restricting the matching IP
+ values is used, the text from the TXT record that is set in $dnslist_text
+ may not reflect the true reason for rejection. This happens when lists are
+ merged and the IP address in the A record is used to distinguish them;
+ unfortunately there is only one TXT record. One way round this is not to
+ use merged lists, but that can be inefficient because it requires multiple
+ DNS lookups where one would do in the vast majority of cases when the host
+ of interest is not on any of the lists.
+
+ A less inefficient way of solving this problem has now been implemented. If
+ two domain names, comma-separated, are given, the second is used first to
+ do an initial check, making use of any IP value restrictions that are set.
+ If there is a match, the first domain is used, without any IP value
+ restrictions, to get the TXT record. As a byproduct of this, there is also
+ a check that the IP being tested is indeed on the first list. The first
+ domain is the one that is put in $dnslist_domain. For example:
+
+ reject message = rejected because $sender_ip_address is blacklisted \
+ at $dnslist_domain\n$dnslist_text
+ dnslists = sbl.spamhaus.org,sbl-xbl.spamhaus.org=127.0.0.2 : \
dul.dnsbl.sorbs.net,dnsbl.sorbs.net=127.0.0.10
- In this case there is a lookup in dnsbl.sorbs.net, and if none of the IP
- values matches (or if no record is found), this is the only lookup that is
- done. Only if there is a match is one of the more specific lists consulted.
-
-6. All authenticators now have a server_condition option. Previously, only
- plaintext had this, and this has not changed: it must be set to the
- authenticator as a server. For the others, if server_condition is set, it is
- expanded if authentication is successful, and treated exactly as it is in
- plaintext. This can serve as a means of adding authorization to an
- authenticator.
-
-7. There is a new command-line option called -Mset. It is useful only in
- conjunction with -be (that is, when testing string expansions). It must be
- followed by a message id; Exim loads the given message from its spool before
- doing the expansions, thus setting message-specific variables such as
- $message_size and the header variables. The $recipients variable is
- available. This feature is provided to make it easier to test expansions
- that make use of these variables. However, Exim must be called by an admin
- user when -Mset is used.
-
-8. Another similar new command-line option is called -bem. It operates like -be
- except that it must be followed by the name of a file. For example:
-
- exim -bem /tmp/testmessage
-
- The file is read as a message (as if receiving a locally-submitted non-SMTP
- message) before any of the test expansions are done. Thus, message-specific
- variables such as $message_size and $h_from: are available. However, no
- Received: header is added to the message. If the -t option is set,
- recipients are read from the headers in the normal way, and are shown in the
- $recipients variable. Note that recipients cannot be given on the command
- line, because further arguments are taken as strings to expand (just like
- -be).
-
-9. When an address is delayed because of a 4xx response to a RCPT command, it
- is now the combination of sender and recipient that is delayed in subsequent
- queue runs until its retry time is reached. You can revert to the previous
- behavious, that is, delay the recipient independent of the sender, by
- setting address_retry_include_sender=false in the smtp transport. However,
- this can lead to problems with servers that regularly issue 4xx responses to
- RCPT commands.
+ For the first blacklist item, this starts by doing a lookup in
+ sbl-xbl.spamhaus.org and testing for a 127.0.0.2 return. If there is a
+ match, it then looks in sbl.spamhaus.org, without checking the return
+ value, and as long as something is found, it looks for the corresponding
+ TXT record. If there is no match in sbl-xbl.spamhaus.org, nothing more is
+ done. The second blacklist item is processed similarly.
+
+ If you are interested in more than one merged list, the same list must be
+ given several times, but because the results of the DNS lookups are cached,
+ the DNS calls themselves are not repeated. For example:
+
+ reject dnslists = http.dnsbl.sorbs.net,dnsbl.sorbs.net=127.0.0.2 : \
+ socks.dnsbl.sorbs.net,dnsbl.sorbs.net=127.0.0.3 : \
+ misc.dnsbl.sorbs.net,dnsbl.sorbs.net=127.0.0.4 : \
+ dul.dnsbl.sorbs.net,dnsbl.sorbs.net=127.0.0.10
+
+ In this case there is a lookup in dnsbl.sorbs.net, and if none of the IP
+ values matches (or if no record is found), this is the only lookup that is
+ done. Only if there is a match is one of the more specific lists consulted.
+
+ 6. All authenticators now have a server_condition option. Previously, only
+ plaintext had this, and this has not changed: it must be set to the
+ authenticator as a server. For the others, if server_condition is set, it
+ is expanded if authentication is successful, and treated exactly as it is
+ in plaintext. This can serve as a means of adding authorization to an
+ authenticator.
+
+ 7. There is a new command-line option called -Mset. It is useful only in
+ conjunction with -be (that is, when testing string expansions). It must be
+ followed by a message id; Exim loads the given message from its spool
+ before doing the expansions, thus setting message-specific variables such
+ as $message_size and the header variables. The $recipients variable is
+ available. This feature is provided to make it easier to test expansions
+ that make use of these variables. However, Exim must be called by an admin
+ user when -Mset is used.
+
+ 8. Another similar new command-line option is called -bem. It operates like
+ -be except that it must be followed by the name of a file. For example:
+
+ exim -bem /tmp/testmessage
+
+ The file is read as a message (as if receiving a locally-submitted non-SMTP
+ message) before any of the test expansions are done. Thus, message-specific
+ variables such as $message_size and $h_from: are available. However, no
+ Received: header is added to the message. If the -t option is set,
+ recipients are read from the headers in the normal way, and are shown in
+ the $recipients variable. Note that recipients cannot be given on the
+ command line, because further arguments are taken as strings to expand
+ (just like -be).
+
+ 9. When an address is delayed because of a 4xx response to a RCPT command, it
+ is now the combination of sender and recipient that is delayed in
+ subsequent queue runs until its retry time is reached. You can revert to
+ the previous behavious, that is, delay the recipient independent of the
+ sender, by setting address_retry_include_sender=false in the smtp
+ transport. However, this can lead to problems with servers that regularly
+ issue 4xx responses to RCPT commands.
+
+10. Unary negation and the bitwise logical operators and, or, xor, not, and
+ shift, have been added to the eval: and eval10: expansion items. These
+ items may now contain arithmetic operators (plus, minus, times, divide,
+ remainder, negate), bitwise operators (and, or, xor, not, shift), and
+ parentheses. All operations are carried out using signed integer
+ arithmetic. Operator priorities are as in C, namely:
+
+ (highest) not, negate
+ times, divide, remainder
+ plus, minus
+ shift-left, shift-right
+ and
+ xor
+ (lowest) or
+
+ Binary operators with the same priority are evaluated from left to right.
+ For example:
+
+ ${eval:1+1} yields 2
+ ${eval:1+2*3} yields 7
+ ${eval:(1+2)*3} yields 9
+ ${eval:2+42%5} yields 4
+ ${eval:0xc&5} yields 4
+ ${eval:0xc|5} yields 13
+ ${eval:0xc^5} yields 9
+ ${eval:0xc>>1} yields 6
+ ${eval:0xc<<1} yields 24
+ ${eval:~255&0x1234} yields 4608
+ ${eval:-(~255&0x1234)} yields -4608
+
+11. The variables $interface_address and $interface_port have been renamed
+ as $received_ip_address and $received_port, to make it clear that they
+ relate to message reception rather than delivery. (The old names remain
+ available for compatibility.)
+
+12. The "message" modifier can now be used on acl verbs to vary the message
+ that is sent when an SMTP command. For example, in a RCPT ACL you could
+ have:
+
+ accept <some conditions>
+ message = OK, I'll allow you through today
+
+ Previously, this message modifier would have had no effect whatsoever.
+
+ IMPORTANT: The new behaviour applies to "accept" (and "discard") only if
+ there is no occurrence of "endpass" in the statement. If "endpass" is
+ present, the behaviour reverts to the old case, where "message" applies to
+ rejection. This is for backwards compatibility.
+
+ It is always possible to rewrite ACL statements so that "endpass" is not
+ needed (and indeed it is no longer used in the default configuration, and
+ is somewhat not recommended nowadays because it causes confusion.)
+
+ It is now generally true that the "message" modifier sets up a text string
+ that is expanded and used as a response message if the current statement
+ terminates the ACL. The expansion happens at the time Exim decides that the
+ ACL is to end, not at the time it processes "message". If the expansion
+ fails, or generates an empty string, the modifier is ignored.
+
+ For ACLs that are triggered by SMTP commands, the message is returned as
+ part of the SMTP response. In this situation, the message may begin with an
+ overriding SMTP response code, optionally followed by an "extended response
+ code". However, the first digit of the supplied response code must be the
+ same as would be sent by default. A panic occurs if it is not. For the
+ predata ACL, note that the default success code is 354, not 2xx.
+
+ However, notwithstanding the previous paragraph, for the QUIT ACL, unlike
+ the others, the message modifier cannot override the 221 response code.
+
+ In the case of the "connect" ACL, accepting with a message modifier
+ overrides the value of smtp_banner.
+
+ The ACL test specified by acl_smtp_helo happens when the client issues the
+ HELO or EHLO commands, after the tests specified by helo_accept_junk_hosts,
+ helo_allow_chars and helo(_try)_verify_hosts. An acceptance message
+ modifier for EHLO/HELO may not contain more than one line (it will be
+ truncated at the first newline and a panic logged), and it cannot affect
+ the EHLO options.
git://git.exim.org / exim.git / blobdiff