-This file contains descriptions of new features that have been added to Exim,
-but have not yet made it into the main manual (which is most conveniently
-updated when there is a relatively large batch of changes). The doc/ChangeLog
-file contains a listing of all changes, including bug fixes.
-
-
-Exim version 4.52
------------------
-
-TF/01 Support for checking Client SMTP Authorization has been added. CSA is a
- system which allows a site to advertise which machines are and are not
- permitted to send email. This is done by placing special SRV records in
- the DNS, which are looked up using the client's HELO domain. At this
- time CSA is still an Internet-Draft.
-
- Client SMTP Authorization checks are performed by the ACL condition
- verify=csa. This will fail if the client is not authorized. If there is
- a DNS problem, or if no valid CSA SRV record is found, or if the client
- is authorized, the condition succeeds. These three cases can be
- distinguished using the expansion variable $csa_status, which can take
- one of the values "fail", "defer", "unknown", or "ok". The condition
- does not itself defer because that would be likely to cause problems
- for legitimate email.
-
- The error messages produced by the CSA code include slightly more
- detail. If $csa_status is "defer" this may be because of problems
- looking up the CSA SRV record, or problems looking up the CSA target
- address record. There are four reasons for $csa_status being "fail":
- the client's host name is explicitly not authorized; the client's IP
- address does not match any of the CSA target IP addresses; the client's
- host name is authorized but it has no valid target IP addresses (e.g.
- the target's addresses are IPv6 and the client is using IPv4); or the
- client's host name has no CSA SRV record but a parent domain has
- asserted that all subdomains must be explicitly authorized.
-
- The verify=csa condition can take an argument which is the domain to
- use for the DNS query. The default is verify=csa/$sender_helo_name.
-
- This implementation includes an extension to CSA. If the query domain
- is an address literal such as [192.0.2.95], or if it is a bare IP
- address, Exim will search for CSA SRV records in the reverse DNS as if
- the HELO domain was e.g. 95.2.0.192.in-addr.arpa. Therefore it is
- meaningful to say, for example, verify=csa/$sender_host_address - in
- fact, this is the check that Exim performs if the client does not say
- HELO. This extension can be turned off by setting the main
- configuration option dns_csa_use_reverse = false.
-
- If a CSA SRV record is not found for the domain itself, then a search
- is performed through its parent domains for a record which might be
- making assertions about subdomains. The maximum depth of this search is
- limited using the main configuration option dns_csa_search_limit, which
- takes the value 5 by default. Exim does not look for CSA SRV records in
- a top level domain, so the default settings handle HELO domains as long
- as seven (hostname.five.four.three.two.one.com) which encompasses the
- vast majority of legitimate HELO domains.
-
- The dnsdb lookup also has support for CSA. Although dnsdb already
- supports SRV lookups, this is not sufficient because of the extra
- parent domain search behaviour of CSA, and (as with PTR lookups)
- dnsdb also turns IP addresses into lookups in the reverse DNS space.
- The result of ${lookup dnsdb {csa=$sender_helo_name} } has two
- space-separated fields: an authorization code and a target host name.
- The authorization code can be "Y" for yes, "N" for no, "X" for explicit
- authorization required but absent, or "?" for unknown.
-
-PH/01 The amount of output produced by the "make" process has been reduced,
- because the compile lines are often rather long, making it all pretty
- unreadable. The new style is along the lines of the 2.6 Linux kernel:
- just a short line for each module that is being compiled or linked.
- However, it is still possible to get the full output, by calling "make"
- like this:
-
- FULLECHO='' make -e
-
- The value of FULLECHO defaults to "@", the flag character that suppresses
- command reflection in "make". When you ask for the full output, it is
- given in addition to the the short output.
-
-TF/02 There have been two changes concerned with submission mode:
-
- Until now submission mode always left the return path alone, whereas
- locally-submitted messages from untrusted users have the return path
- fixed to the user's email address. Submission mode now fixes the return
- path to the same address as is used to create the Sender: header. If
- /sender_retain is specified then both the Sender: header and the return
- path are left alone.
-
- Note that the changes caused by submission mode take effect after the
- predata ACL. This means that any sender checks performed before the
- fix-ups will use the untrusted sender address specified by the user, not
- the trusted sender address specified by submission mode. Although this
- might be slightly unexpected, it does mean that you can configure ACL
- checks to spot that a user is trying to spoof another's address, for
- example.
-
- There is also a new /name= option for submission mode which allows you
- to specify the user's full name to be included in the Sender: header.
- For example:
-
- accept authenticated = *
- control = submission/name=${lookup {$authenticated_id} \
- lsearch {/etc/exim/namelist} }
-
- The namelist file contains entries like
-
- fanf: Tony Finch
-
- And the resulting Sender: header looks like
-
- Sender: Tony Finch <fanf@exim.org>
-
-TF/03 The control = fakereject ACL modifier now has a fakedefer counterpart,
- which works in exactly the same way except it causes a fake SMTP 450
- response after the message data instead of a fake SMTP 550 response.
- You must take care when using fakedefer because it will cause messages
- to be duplicated when the sender retries. Therefore you should not use
- fakedefer if the message will be delivered normally.
-
-TF/04 There is a new ratelimit ACL condition which can be used to measure
- and control the rate at which clients can send email. This is more
- powerful than the existing smtp_ratelimit_* options, because those
- options only control the rate of commands in a single SMTP session,
- whereas the new ratelimit condition works across all connections
- (concurrent and sequential) to the same host.
-
- The syntax of the ratelimit condition is:
-
- ratelimit = <m> / <p> / <options> / <key>
-
- If the average client sending rate is greater than m messages per time
- period p then the condition is true, otherwise it is false.
-
- The parameter p is the smoothing time constant, in the form of an Exim
- time interval e.g. 8h for eight hours. A larger time constant means it
- takes Exim longer to forget a client's past behaviour. The parameter m is
- the maximum number of messages that a client can send in a fast burst. By
- increasing both m and p but keeping m/p constant, you can allow a client
- to send more messages in a burst without changing its overall sending
- rate limit. Conversely, if m and p are both small then messages must be
- sent at an even rate.
-
- The key is used to look up the data used to calcluate the client's
- average sending rate. This data is stored in a database maintained by
- Exim in its spool directory alongside the retry database etc. For
- example, you can limit the sending rate of each authenticated user,
- independent of the computer they are sending from, by setting the key
- to $authenticated_id. The default key is $sender_host_address.
-
- Each ratelimit condition can have up to two options. The first option
- specifies what Exim measures the rate of, and the second specifies how
- Exim handles excessively fast clients.
-
- The per_mail option means that it measures the client's rate of sending
- messages. This is the default if none of the per_* options is specified.
-
- The per_conn option means that it measures the client's connection rate.
-
- The per_byte option limits the sender's email bandwidth. Note that it
- is best to use this option in the DATA ACL; if it is used in an earlier
- ACL it relies on the SIZE parameter on the MAIL command, which may be
- inaccurate or completely missing. You can follow the limit m in the
- configuration with K, M, or G to specify limits in kilobytes,
- megabytes, or gigabytes respectively.
-
- The per_cmd option means that Exim recomputes the rate every time the
- condition is processed, which can be used to limit the SMTP command rate.
- The alias per_rcpt is provided for use in the RCPT ACL instead of per_cmd
- to make it clear that the effect is to limit the rate at which recipients
- are accepted. Note that in this case the rate limiting engine will see a
- message with many recipients as a large high-speed burst.
-
- If a client's average rate is greater than the maximum, the rate
- limiting engine can react in two possible ways, depending on the
- presence of the strict or leaky options. This is independent of the
- other counter-measures (e.g. rejecting the message) that may be
- specified by the rest of the ACL. The default mode is leaky, which
- avoids a sender's over-aggressive retry rate preventing it from getting
- any email through.
-
- The strict option means that the client's recorded rate is always
- updated. The effect of this is that Exim measures the client's average
- rate of attempts to send email, which can be much higher than the
- maximum. If the client is over the limit it will be subjected to
- counter-measures until it slows down below the maximum rate.
-
- The leaky option means that the client's recorded rate is not updated
- if it is above the limit. The effect of this is that Exim measures the
- client's average rate of successfully sent email, which cannot be
- greater than the maximum. If the client is over the limit it will
- suffer some counter-measures, but it will still be able to send email
- at the configured maximum rate, whatever the rate of its attempts.
-
- As a side-effect, the ratelimit condition will set the expansion
- variables $sender_rate containing the client's computed rate,
- $sender_rate_limit containing the configured value of m, and
- $sender_rate_period containing the configured value of p.
-
- Exim's other ACL facilities are used to define what counter-measures
- are taken when the rate limit is exceeded. This might be anything from
- logging a warning (e.g. while measuring existing sending rates in order
- to define our policy), through time delays to slow down fast senders,
- up to rejecting the message. For example,
-
- # Log all senders' rates
- warn
- ratelimit = 0 / 1h / strict
- log_message = \
- Sender rate $sender_rate > $sender_rate_limit / $sender_rate_period
-
- # Slow down fast senders
- warn
- ratelimit = 100 / 1h / per_rcpt / strict
- delay = ${eval: 10 * ($sender_rate - $sender_rate_limit) }
-
- # Keep authenticated users under control
- deny
- ratelimit = 100 / 1d / strict / $authenticated_id
-
- # System-wide rate limit
- defer
- message = Sorry, too busy. Try again later.
- ratelimit = 10 / 1s / $primary_hostname
-
- # Restrict incoming rate from each host, with a default rate limit
- # set using a macro and special cases looked up in a table.
- defer
- message = Sender rate $sender_rate exceeds \
- $sender_rate_limit messages per $sender_rate_period
- ratelimit = ${lookup {$sender_host_address} \
- cdb {DB/ratelimits.cdb} \
- {$value} {RATELIMIT} }
-
-
-Version 4.51
+This file contains descriptions of new features that have been added to Exim.
+Before a formal release, there may be quite a lot of detail so that people can
+test from the snapshots or the CVS before the documentation is updated. Once
+the documentation is updated, this file is reduced to a short list.
+
+Version 4.68
+------------
+
+ 1. The body_linecount and body_zerocount C variables are now exported in the
+ local_scan API.
+
+ 2. When a dnslists lookup succeeds, the key that was looked up is now placed
+ in $dnslist_matched. When the key is an IP address, it is not reversed in
+ this variable (though it is, of course, in the actual lookup). In simple
+ cases, for example:
+
+ deny dnslists = spamhaus.example
+
+ the key is also available in another variable (in this case,
+ $sender_host_address). In more complicated cases, however, this is not
+ true. For example, using a data lookup might generate a dnslists lookup
+ like this:
+
+ deny dnslists = spamhaus.example/<|192.168.1.2|192.168.6.7|...
+
+ If this condition succeeds, the value in $dnslist_matched might be
+ 192.168.6.7 (for example).
+
+ 3. Authenticators now have a client_condition option. When Exim is running as
+ a client, it skips an authenticator whose client_condition expansion yields
+ "0", "no", or "false". This can be used, for example, to skip plain text
+ authenticators when the connection is not encrypted by a setting such as:
+
+ client_condition = ${if !eq{$tls_cipher}{}}
+
+ Note that the 4.67 documentation states that $tls_cipher contains the
+ cipher used for incoming messages. In fact, during SMTP delivery, it
+ contains the cipher used for the delivery. The same is true for
+ $tls_peerdn.
+
+ 4. There is now a -Mvc <message-id> option, which outputs a copy of the
+ message to the standard output, in RFC 2822 format. The option can be used
+ only by an admin user.
+
+ 5. There is now a /noupdate option for the ratelimit ACL condition. It
+ computes the rate and checks the limit as normal, but it does not update
+ the saved data. This means that, in relevant ACLs, it is possible to lookup
+ the existence of a specified (or auto-generated) ratelimit key without
+ incrementing the ratelimit counter for that key.
+
+ In order for this to be useful, another ACL entry must set the rate
+ for the same key somewhere (otherwise it will always be zero).
+
+ Example:
+
+ acl_check_connect:
+ # Read the rate; if it doesn't exist or is below the maximum
+ # we update it below
+ deny ratelimit = 100 / 5m / strict / noupdate
+ log_message = RATE: $sender_rate / $sender_rate_period \
+ (max $sender_rate_limit)
+
+ [... some other logic and tests...]
+
+ warn ratelimit = 100 / 5m / strict / per_cmd
+ log_message = RATE UPDATE: $sender_rate / $sender_rate_period \
+ (max $sender_rate_limit)
+ condition = ${if le{$sender_rate}{$sender_rate_limit}}
+
+ accept
+
+
+Version 4.67
+------------
+
+ 1. There is a new log selector called smtp_no_mail, which is not included in
+ the default setting. When it is set, a line is written to the main log
+ whenever an accepted SMTP connection terminates without having issued a
+ MAIL command.
+
+ 2. When an item in a dnslists list is followed by = and & and a list of IP
+ addresses, the behaviour was not clear when the lookup returned more than
+ one IP address. This has been solved by the addition of == and =& for "all"
+ rather than the default "any" matching.
+
+ 3. Up till now, the only control over which cipher suites GnuTLS uses has been
+ for the cipher algorithms. New options have been added to allow some of the
+ other parameters to be varied.
+
+ 4. There is a new compile-time option called ENABLE_DISABLE_FSYNC. When it is
+ set, Exim compiles a runtime option called disable_fsync.
+
+ 5. There is a new variable called $smtp_count_at_connection_start.
+
+ 6. There's a new control called no_pipelining.
+
+ 7. There are two new variables called $sending_ip_address and $sending_port.
+ These are set whenever an SMTP connection to another host has been set up.
+
+ 8. The expansion of the helo_data option in the smtp transport now happens
+ after the connection to the server has been made.
+
+ 9. There is a new expansion operator ${rfc2047d: that decodes strings that
+ are encoded as per RFC 2047.
+
+10. There is a new log selector called "pid", which causes the current process
+ id to be added to every log line, in square brackets, immediately after the
+ time and date.
+
+11. Exim has been modified so that it flushes SMTP output before implementing
+ a delay in an ACL. It also flushes the output before performing a callout,
+ as this can take a substantial time. These behaviours can be disabled by
+ obeying control = no_delay_flush or control = no_callout_flush,
+ respectively, at some earlier stage of the connection.
+
+12. There are two new expansion conditions that iterate over a list. They are
+ called forany and forall.
+
+13. There's a new global option called dsn_from that can be used to vary the
+ contents of From: lines in bounces and other automatically generated
+ messages ("delivery status notifications" - hence the name of the option).
+
+14. The smtp transport has a new option called hosts_avoid_pipelining.
+
+15. By default, exigrep does case-insensitive matches. There is now a -I option
+ that makes it case-sensitive.
+
+16. A number of new features ("addresses", "map", "filter", and "reduce") have
+ been added to string expansions to make it easier to process lists of
+ items, typically addresses.
+
+17. There's a new ACL modifier called "continue". It does nothing of itself,
+ and processing of the ACL always continues with the next condition or
+ modifier. It is provided so that the side effects of expanding its argument
+ can be used.
+
+18. It is now possible to use newline and other control characters (those with
+ values less than 32, plus DEL) as separators in lists.
+
+19. The exigrep utility now has a -v option, which inverts the matching
+ condition.
+
+20. The host_find_failed option in the manualroute router can now be set to
+ "ignore".
+
+
+Version 4.66
+------------
+
+No new features were added to 4.66.
+
+
+Version 4.65
+------------
+
+No new features were added to 4.65.
+
+
+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.
+
+ 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.
+
+ 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.
+
+ 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, 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.
+
+ 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 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.
+
+10. Unary negation and the bitwise logical operators and, or, xor, not, and
+ 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 "accept" and "discard" acl verbs
+ to vary the message that is sent when an SMTP command is accepted.
+
+
+Version 4.63
+------------
+
+1. There is a new Boolean option called filter_prepend_home for the redirect
+ router.
+
+2. There is a new acl, set by acl_not_smtp_start, which is run right at the
+ start of receiving a non-SMTP message, before any of the message has been
+ read.
+
+3. When an SMTP error message is specified in a "message" modifier in an ACL,
+ or in a :fail: or :defer: message in a redirect router, Exim now checks the
+ start of the message for an SMTP error code.
+
+4. There is a new parameter for LDAP lookups called "referrals", which takes
+ one of the settings "follow" (the default) or "nofollow".
+
+5. Version 20070721.2 of exipick now included, offering these new options:
+ --reverse
+ After all other sorting options have bee processed, reverse order
+ before displaying messages (-R is synonym).
+ --random
+ Randomize order of matching messages before displaying.
+ --size
+ Instead of displaying the matching messages, display the sum
+ of their sizes.
+ --sort <variable>[,<variable>...]
+ Before displaying matching messages, sort the messages according to
+ each messages value for each variable.
+ --not
+ Negate the value for every test (returns inverse output from the
+ same criteria without --not).
+
+
+Version 4.62
git://git.exim.org / exim.git / blobdiff