-$Cambridge: exim/doc/doc-txt/NewStuff,v 1.124 2006/12/05 11:35:28 ph10 Exp $
+$Cambridge: exim/doc/doc-txt/NewStuff,v 1.125 2006/12/20 09:44:37 ph10 Exp $
New Features in Exim
--------------------
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.
+ an underscore.
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.
+ to specify which logs are used for messages about ACL 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.
+ number of authentication methods.
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 : \
- 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.
+ 5. In a DNS black list, 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.
+
+ 6. All authenticators now have a server_condition option.
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.
+ before doing the expansions.
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).
+ -be except that it must be followed by the name of a file that contains a
+ message.
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.
+ subsequent queue runs until its retry time is reached.
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
+ shift, have been added to the eval: and eval10: expansion items.
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 is accepted. 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.
-
+12. The "message" modifier can now be used on "accept" and "discard" acl verbs
+ to vary the message that is sent when an SMTP command is accepted.
Version 4.63
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