ph10 2005/11/21 09:51:21 GMT
Modified files:
exim-doc/doc-txt NewStuff
Log:
Update for 4.60.
Revision Changes Path
1.77 +11 -740 exim/exim-doc/doc-txt/NewStuff
Index: NewStuff
===================================================================
RCS file: /home/cvs/exim/exim-doc/doc-txt/NewStuff,v
retrieving revision 1.76
retrieving revision 1.77
diff -u -r1.76 -r1.77
--- NewStuff 3 Oct 2005 13:25:32 -0000 1.76
+++ NewStuff 21 Nov 2005 09:51:21 -0000 1.77
@@ -1,4 +1,4 @@
-$Cambridge: exim/exim-doc/doc-txt/NewStuff,v 1.76 2005/10/03 13:25:32 ph10 Exp $
+$Cambridge: exim/exim-doc/doc-txt/NewStuff,v 1.77 2005/11/21 09:51:21 ph10 Exp $
New Features in Exim
--------------------
@@ -8,755 +8,26 @@
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 4.54
------------------
+Version 4.60
+------------
-There was a problem with 4.52/TF/02 in that a "name=" option on control=
-submission terminated at the next slash, thereby not allowing for slashes in
-the name. This has been changed so that "name=" takes the rest of the string as
-its data. It must therefore be the last option.
-
-
-
-Exim version 4.53
------------------
-
-TK/01 Added the "success_on_redirect" address verification option. When an
- address generates new addresses during routing, Exim will abort
- verification with "success" when more than one address has been
- generated, but continue to verify a single new address. The latter
- does not happen when the new "success_on_redirect" option is set, like
-
- require verify = recipient/success_on_redirect/callout=10s
-
- In that case, verification will succeed when a router generates a new
- address.
-
-PH/01 Support for SQLite database lookups has been added. This is another
- query-style lookup, but it is slightly different from the others because
- a file name is required in addition to the SQL query. This is because an
- SQLite database is a single file and there is no daemon as in other SQL
- databases. The interface to Exim requires the name of the file, as an
- absolute path, to be given at the start of the query. It is separated
- from the query by white space. This means that the path name cannot
- contain white space. Here is a lookup expansion example:
-
- ${lookup sqlite {/some/thing/sqlitedb \
- select name from aliases where id='ph10';}}
-
- In a list, the syntax is similar. For example:
-
- domainlist relay_domains = sqlite;/some/thing/sqlitedb \
- select * from relays where ip='$sender_host_address';
-
- The only character affected by the ${quote_sqlite: operator is a single
- quote, which it doubles.
-
- The SQLite library handles multiple simultaneous accesses to the database
- internally. Multiple readers are permitted, but only one process can
- update at once. Attempts to access the database while it is being updated
- are rejected after a timeout period, during which the SQLite library
- waits for the lock to be released. In Exim, the default timeout is set
- to 5 seconds, but it can be changed by means of the sqlite_lock_timeout
- option.
-
- Note that you must set LOOKUP_SQLITE=yes in Local/Makefile in order to
- obtain SQLite support, and you will also need to add -lsqlite3 to the
- EXTRALIBS setting. And of course, you have to install SQLite on your
- host first.
-
-PH/02 The variable $message_id is now deprecated, to be replaced by
- $message_exim_id, which makes it clearer which ID is being referenced.
-
-PH/03 The use of forbid_filter_existstest now also locks out the use of the
- ${stat: expansion item.
-
-PH/04 The IGNOREQUOTA extension to the LMTP protocol is now available in both
- the lmtp transport and the smtp transport running in LMTP mode. In the
- lmtp transport there is a new Boolean option called ignore_quota, and in
- the smtp transport there is a new Boolean option called
- lmtp_ignore_quota. If either of these options is set TRUE, the string
- "IGNOREQUOTA" is added to RCPT commands when using the LMTP protocol,
- provided that the server has advertised support for IGNOREQUOTA in its
- response to the LHLO command.
-
-PH/05 Previously, if "verify = helo" was set in an ACL, the condition was true
- only if the host matched helo_try_verify_hosts, which caused the
- verification to occur when the EHLO/HELO command was issued. The ACL just
- tested the remembered result. Now, if a previous verification attempt has
- not happened, "verify = helo" does it there and then.
-
-PH/06 It is now possible to specify a port number along with a host name or
- IP address in the list of hosts defined in the manualroute or
- queryprogram routers, fallback_hosts, or the "hosts" option of the smtp
- transport. These all override any port specification on the transport.
- The relatively standard syntax of using a colon separator has been
- adopted, but there are some gotchas that need attention:
-
- * In all these lists of hosts, colon is the default separator, so either
- the colon that specifies a port must be doubled, or the separator must
- be changed. The following two examples have the same effect:
-
- fallback_hosts = host1.tld::1225 : host2.tld::1226
- fallback_hosts = <; host1.tld:1225 ; host2.tld:1226
-
- * When IPv6 addresses are involved, it gets worse, because they contain
- colons of their own. To make this case easier, it is permitted to
- enclose an IP address (either v4 or v6) in square brackets if a port
- number follows. Here's an example from a manualroute router:
-
- route_list = * "</ [10.1.1.1]:1225 / [::1]:1226"
-
- If the "/MX" feature is to be used as well as a port specifier, the port
- must come last. For example:
-
- route_list = * dom1.tld/mx::1225
-
-PH/07 $smtp_command_argument is now set for all SMTP commands, not just the
- non-message ones. This makes it possible to inspect the complete command
- for RCPT commands, for example. But see also PH/45 below.
-
-PH/08 The ${eval expansion now supports % as a "remainder" operator.
-
-PH/09 There is a new ACL condition "verify = not_blind". It checks that there
- are no blind (bcc) recipients in the message. Every envelope recipient
- must appear either in a To: header line or in a Cc: header line for this
- condition to be true. Local parts are checked case-sensitively; domains
- are checked case-insensitively. If Resent-To: or Resent-Cc: header lines
- exist, they are also checked. This condition can be used only in a DATA
- or non-SMTP ACL.
-
- There are, of course, many legitimate messages that make use of blind
- (bcc) recipients. This check should not be used on its own for blocking
- messages.
-
-PH/10 There is a new ACL control called "suppress_local_fixups". This applies
- to locally submitted (non TCP/IP) messages, and is the complement of
- "control = submission". It disables the fixups that are normally applied
- to locally-submitted messages. Specifically:
-
- (a) Any Sender: header line is left alone (in this respect, it's a
- dynamic version of local_sender_retain).
-
- (b) No Message-ID:, From:, or Date: headers are added.
-
- (c) There is no check that From: corresponds to the actual sender.
-
- This feature may be useful when a remotely-originated message is
- accepted, passed to some scanning program, and then re-submitted for
- delivery. It means that all four possibilities can now be specified:
-
- (1) Locally submitted, fixups applies: the default.
- (2) Locally submitted, no fixups applied: use control =
- suppress_local_fixups.
- (3) Remotely submitted, no fixups applied: the default.
- (4) Remotely submitted, fixups applied: use control = submission.
-
-PH/11 There is a new log selector, "unknown_in_list", which provokes a log
- entry when the result of a list match is failure because a DNS lookup
- failed.
-
-PH/12 There is a new variable called $smtp_command which contains the full SMTP
- command (compare $smtp_command_argument - see PH/07 above). This makes it
- possible to distinguish between HELO and EHLO, and also between things
- like "MAIL FROM:<>" and "MAIL FROM: <>".
-
-TF/01 There's a new script in util/ratelimit.pl which extracts sending
- rates from log files, to assist with choosing appropriate settings
- when deploying the ratelimit ACL condition.
-
-PH/13 A new letter, "H", is available in retry parameter sets. It is similar
- to "G" (geometric increasing time intervals), except that the interval
- before the next retry is randomized. Each time, the previous interval is
- multiplied by the factor in order to get a maximum for the next interval.
- The mininum interval is the first argument of the parameter, and an
- actual interval is chosen randomly between them. Such a rule has been
- found to be helpful in cluster configurations when all the members of the
- cluster restart at once, and may synchronize their queue processing
- times.
-
-PH/14 The options never_users, trusted_users, admin_groups, and trusted_groups
- are now expanded when the configuration file is read.
-
-
-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@???>
-
-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 less than m messages per time
- period p then the condition is false, otherwise it is true.
-
- 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 calculate 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.
- Internally, Exim includes the smoothing constant p and the options in
- the lookup key because they alter the meaning of the stored data.
- This is not true for the limit m, so you can alter the configured
- maximum rate and Exim will still remember clients' past behaviour,
- but if you alter the other ratelimit parameters Exim will effectively
- forget their past behaviour.
-
- 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 options are separated by a
- slash, like the other parameters.
-
- 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
- smoothing period determines the time it takes for a high sending rate
- to decay exponentially to 37% of its peak value, which means that you
- can work out the time (the number of smoothing periods) that a client
- is subjected to counter-measures after an over-limit burst with the
- formula ln(peakrate/maxrate).
-
- 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_period
-
- # Slow down fast senders
- warn
- ratelimit = 100 / 1h / per_rcpt / strict
- delay = ${eval: $sender_rate - $sender_rate_limit }s
-
- # 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 exceeds $sender_rate_limit \
- messages per $sender_rate_period
- ratelimit = ${lookup {$sender_host_address} \
- cdb {DB/ratelimits.cdb} \
- {$value} {RATELIMIT} }
-
- Warning: if you have a busy server with a lot of ratelimit tests,
- especially with the per_rcpt option, you may suffer from a performance
- bottleneck caused by locking on the ratelimit hints database. Apart from
- making your ACLs less complicated, you can reduce the problem by using a
- RAM disk for Exim's hints directory, /var/spool/exim/db/. However this
- means that Exim will lose its hints data after a reboot (including retry
- hints, the callout cache, and ratelimit data).
-
-TK/01 Added an 'spf' lookup type that will return an SPF result for a given
- email address (the key) and an IP address (the database):
-
- ${lookup {tom@???} spf{217.115.139.137}}
-
- The lookup will return the same result strings as they can appear in
- $spf_result (pass,fail,softfail,neutral,none,err_perm,err_temp). The
- lookup is armored in EXPERIMENTAL_SPF. Currently, only IPv4 addresses
- are supported.
-
- Patch submitted by Chris Webb <chris@???>.
-
-PH/02 There's a new verify callout option, "fullpostmaster", which first acts
- as "postmaster" and checks the recipient <postmaster@domain>. If that
- fails, it tries just <postmaster>, without a domain, in accordance with
- the specification in RFC 2821.
-
-PH/03 The action of the auto_thaw option has been changed. It no longer applies
- to frozen bounce messages.
-
-TK/02 There are two new expansion items to help with the implementation of
- the BATV "prvs" scheme in an Exim configuration:
-
-
- ${prvs {<ADDRESS>}{<KEY>}{[KEYNUM]}}
-
- The "prvs" expansion item takes three arguments: A qualified RFC2821
- email address, a key and an (optional) key number. All arguments are
- expanded before being used, so it is easily possible to lookup a key
- and key number using the address as the lookup key. The key number is
- optional and defaults to "0". The item will expand to a "prvs"-signed
- email address, to be typically used with the "return_path" option on
- a smtp transport. The decision if BATV should be used with a given
- sender/recipient pair should be done on router level, to avoid having
- to set "max_rcpt = 1" on the transport.
-
-
- ${prvscheck {<ADDRESS>}{<SECRET>}{<RETURN_STRING>}}
-
- The "prvscheck" expansion item takes three arguments. Argument 1 is
- expanded first. When the expansion does not yield a SYNTACTICALLY
- valid "prvs"-scheme address, the whole "prvscheck" item expands to
- the empty string. If <ADDRESS> is a "prvs"-encoded address after
- expansion, two expansion variables are set up:
-
- $prvscheck_address Contains the "prvs"-decoded version of
- the address from argument 1.
-
- $prvscheck_keynum Contains the key number extracted from
- the "prvs"-address in argument 1.
-
- These two variables can be used in the expansion code of argument 2
- to retrieve the <SECRET>. The VALIDITY of the "prvs"-signed address
- is then checked. The result is stored in yet another expansion
- variable:
-
- $prvscheck_result Contains the result of a "prvscheck"
- expansion: Unset (the empty string) for
- failure, "1" for success.
-
- The "prvscheck" expansion expands to the empty string if <ADDRESS>
- is not a SYNTACTICALLY valid "prvs"-scheme address. Otherwise,
- argument 3 defines what "prvscheck" expands to: If argument 3
- is the empty string, "prvscheck" expands to the decoded version
- of the address (no matter if it is CRYPTOGRAPHICALLY valid or not).
- If argument 3 expands to a non-empty string, "prvscheck" expands
- to that string.
-
-
- Usage example
- -------------
-
- Macro:
-
- PRVSCHECK_SQL = ${lookup mysql{SELECT secret FROM batv_prvs WHERE \
- sender='${quote_mysql:$prvscheck_address}'}{$value}}
-
- RCPT ACL:
-
- # Bounces: drop unsigned addresses for BATV senders
- deny message = This address does not send an unsigned reverse path.
- senders = :
- recipients = +batv_recipients
-
- # Bounces: In case of prvs-signed address, check signature.
- deny message = Invalid reverse path signature.
- senders = :
- condition = ${prvscheck {$local_part@$domain}{PRVSCHECK_SQL}{1}}
- !condition = $prvscheck_result
-
- Top-Level Router:
-
- batv_redirect:
- driver = redirect
- data = ${prvscheck {$local_part@$domain}{PRVSCHECK_SQL}{}}
-
- Transport (referenced by router that makes decision if
- BATV is applicable):
-
- external_smtp_batv:
- driver = smtp
- return_path = ${prvs {$return_path} \
- {${lookup mysql{SELECT \
- secret FROM batv_prvs WHERE \
- sender='${quote_mysql:$sender_address}'} \
- {$value}fail}}}
-
-PH/04 There are two new options that control the retrying done by the daemon
- at startup when it cannot immediately bind a socket (typically because
- the socket is already in use). The default values reproduce what were
- built-in constants previously: daemon_startup_retries defines the number
- of retries after the first failure (default 9); daemon_startup_sleep
- defines the length of time to wait between retries (default 30s).
-
-PH/05 There is now a new ${if condition called "match_ip". It is similar to
- match_domain, etc. It must be followed by two argument strings. The first
- (after expansion) must be an IP address or an empty string. The second
- (after expansion) is a restricted host list that can match only an IP
- address, not a host name. For example:
-
- ${if match_ip{$sender_host_address}{1.2.3.4:5.6.7.8}{...}{...}}
-
- The specific types of host list item that are permitted in the list are
- shown below. Consult the manual section on host lists for further
- details.
-
- . An IP address, optionally with a CIDR mask.
-
- . A single asterisk matches any IP address.
-
- . An empty item matches only if the IP address is empty. This could be
- useful for testing for a locally submitted message or one from specific
- hosts in a single test such as
-
- ${if match_ip{$sender_host_address}{:4.3.2.1:...}{...}{...}}
-
- where the first item in the list is the empty string.
-
- . The item @[] matches any of the local host's interface addresses.
-
- . Lookups are assumed to be "net-" style lookups, even if "net-" is not
- specified. Thus, the following are equivalent:
-
- ${if match_ip{$sender_host_address}{lsearch;/some/file}...
- ${if match_ip{$sender_host_address}{net-lsearch;/some/file}...
-
- You do need to specify the "net-" prefix if you want to specify a
- specific address mask, for example, by using "net24-".
-
-PH/06 The "+all" debug selector used to set the flags for all possible output;
- it is something that people tend to use semi-automatically when
- generating debug output for me or for the list. However, by including
- "+memory", an awful lot of output that is very rarely of interest was
- generated. I have changed this so that "+all" no longer includes
- "+memory". However, "-all" still turns everything off.
+The documentation is up-to-date for the 4.60 release. Major new features since
+the 4.50 release are:
+. Support for SQLite.
-Version 4.51
-------------
+. Support for IGNOREQUOTA in LMTP.
-PH/01 The format in which GnuTLS parameters are written to the gnutls-param
- file in the spool directory has been changed. This change has been made
- to alleviate problems that some people had with the generation of the
- parameters by Exim when /dev/random was exhausted. In this situation,
- Exim would hang until /dev/random acquired some more entropy.
-
- The new code exports and imports the DH and RSA parameters in PEM
- format. This means that the parameters can be generated externally using
- the certtool command that is part of GnuTLS.
-
- To replace the parameters with new ones, instead of deleting the file
- and letting Exim re-create it, you can generate new parameters using
- certtool and, when this has been done, replace Exim's cache file by
- renaming. The relevant commands are something like this:
-
- # rm -f new.params
- # touch new.params
- # chown exim:exim new.params
- # chmod 0400 new.params
- # certtool --generate-privkey --bits 512 >new.params
- # echo "" >>new.params
- # certtool --generate-dh-params --bits 1024 >> new.params
- # mv new.params params
-
- If Exim never has to generate the parameters itself, the possibility of
- stalling is removed.
-
-PH/02 A new expansion item for dynamically loading and calling a locally-
- written C function is now provided, if Exim is compiled with
-
- EXPAND_DLFUNC=yes
-
- set in Local/Makefile. The facility is not included by default (a
- suitable error is given if you try to use it when it is not there.)
-
- If you enable EXPAND_DLFUNC, you should also be aware of the new redirect
- router option forbid_filter_dlfunc. If you have unprivileged users on
- your system who are permitted to create filter files, you might want to
- set forbid_filter_dlfunc=true in the appropriate router, to stop them
- using ${dlfunc to run code within Exim.
-
- You load and call an external function like this:
-
- ${dlfunc{/some/file}{function}{arg1}{arg2}...}
-
- Once loaded, Exim remembers the dynamically loaded object so that it
- doesn't reload the same object file in the same Exim process (but of
- course Exim does start new processes frequently).
-
- There may be from zero to eight arguments to the function. When compiling
- a local function that is to be called in this way, local_scan.h should be
- included. The Exim variables and functions that are defined by that API
- are also available for dynamically loaded functions. The function itself
- must have the following type:
-
- int dlfunction(uschar **yield, int argc, uschar *argv[])
-
- Where "uschar" is a typedef for "unsigned char" in local_scan.h. The
- function should return one of the following values:
-
- OK Success. The string that is placed in "yield" is put into
- the expanded string that is being built.
-
- FAIL A non-forced expansion failure occurs, with the error
- message taken from "yield", if it is set.
-
- FAIL_FORCED A forced expansion failure occurs, with the error message
- taken from "yield" if it is set.
-
- ERROR Same as FAIL, except that a panic log entry is written.
-
- When compiling a function that is to be used in this way with gcc,
- you need to add -shared to the gcc command. Also, in the Exim build-time
- configuration, you must add -export-dynamic to EXTRALIBS.
-
-TF/01 $received_time is a new expansion variable containing the time and date
- as a number of seconds since the start of the Unix epoch when the
- current message was received.
-
-PH/03 There is a new value for RADIUS_LIB_TYPE that can be set in
- Local/Makefile. It is RADIUSCLIENTNEW, and it requests that the new API,
- in use from radiusclient 0.4.0 onwards, be used. It does not appear to be
- possible to detect the different versions automatically.
-
-PH/04 There is a new option called acl_not_smtp_mime that allows you to scan
- MIME parts in non-SMTP messages. It operates in exactly the same way as
- acl_smtp_mime
-
-PH/05 It is now possible to redefine a macro within the configuration file.
- The macro must have been previously defined within the configuration (or
- an included file). A definition on the command line using the -D option
- causes all definitions and redefinitions within the file to be ignored.
- In other words, -D overrides any values that are set in the file.
- Redefinition is specified by using '==' instead of '='. For example:
-
- MAC1 = initial value
- ...
- MAC1 == updated value
-
- Redefinition does not alter the order in which the macros are applied to
- the subsequent lines of the configuration file. It is still the same
- order in which the macros were originally defined. All that changes is
- the macro's value. Redefinition makes it possible to accumulate values.
- For example:
-
- MAC1 = initial value
- ...
- MAC1 == MAC1 and something added
-
- This can be helpful in situations where the configuration file is built
- from a number of other files.
-
-PH/06 Macros may now be defined or redefined between router, transport,
- authenticator, or ACL definitions, as well as in the main part of the
- configuration. They may not, however, be changed within an individual
- driver or ACL, or in the local_scan, retry, or rewrite sections of the
- configuration.
-
-PH/07 $acl_verify_message is now set immediately after the failure of a
- verification in an ACL, and so is available in subsequent modifiers. In
- particular, the message can be preserved by coding like this:
-
- warn !verify = sender
- set acl_m0 = $acl_verify_message
-
- Previously, $acl_verify_message was set only while expanding "message"
- and "log_message" when a very denied access.
-
-PH/08 The redirect router has two new options, sieve_useraddress and
- sieve_subaddress. These are passed to a Sieve filter to specify the :user
- and :subaddress parts of an address. Both options are unset by default.
- However, when a Sieve filter is run, if sieve_useraddress is unset, the
- entire original local part (including any prefix or suffix) is used for
- :user. An unset subaddress is treated as an empty subaddress.
-
-PH/09 Quota values can be followed by G as well as K and M.
-
-PH/10 $message_linecount is a new variable that contains the total number of
- lines in the header and body of the message. Compare $body_linecount,
- which is the count for the body only. During the DATA and
- content-scanning ACLs, $message_linecount contains the number of lines
- received. Before delivery happens (that is, before filters, routers, and
- transports run) the count is increased to include the Received: header
- line that Exim standardly adds, and also any other header lines that are
- added by ACLs. The blank line that separates the message header from the
- body is not counted. Here is an example of the use of this variable in a
- DATA ACL:
-
- deny message = Too many lines in message header
- condition = \
- ${if <{250}{${eval: $message_linecount - $body_linecount}}}
-
- In the MAIL and RCPT ACLs, the value is zero because at that stage the
- message has not yet been received.
-
-PH/11 In a ${run expansion, the variable $value (which contains the standard
- output) is now also usable in the "else" string.
-
-PH/12 In a pipe transport, although a timeout while waiting for the pipe
- process to complete was treated as a delivery failure, a timeout while
- writing the message to the pipe was logged, but erroneously treated as a
- successful delivery. Such timeouts include transport filter timeouts. For
- consistency with the overall process timeout, these timeouts are now
- treated as errors, giving rise to delivery failures by default. However,
- there is now a new Boolean option for the pipe transport called
- timeout_defer, which, if set TRUE, converts the failures into defers for
- both kinds of timeout. A transport filter timeout is now identified in
- the log output.
+. Extensions to the "submission mode" features.
+. Support for Client SMTP Authorization (CSA).
-Version 4.50
-------------
+. Support for ratelimiting hosts and users.
+
+. New expansion items to help with the BATV "prvs" scheme.
+
+. A "match_ip" condition, that matches an IP address against a list.
-The documentation is up-to-date for the 4.50 release.
+There are many more minor changes.
****
