-$Cambridge: exim/doc/doc-txt/NewStuff,v 1.61 2005/08/02 15:19:20 ph10 Exp $
+$Cambridge: exim/doc/doc-txt/NewStuff,v 1.75 2005/09/22 12:58:14 fanf2 Exp $
New Features in Exim
--------------------
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
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
-----------------
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
+ 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,
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.
+ 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.
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.
+ 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
# Log all senders' rates
warn
ratelimit = 0 / 1h / strict
- log_message = \
- Sender rate $sender_rate > $sender_rate_limit / $sender_rate_period
+ log_message = Sender rate $sender_rate / $sender_rate_period
# Slow down fast senders
warn
ratelimit = 100 / 1h / per_rcpt / strict
- delay = ${eval: 10 * ($sender_rate - $sender_rate_limit) }
+ delay = ${eval: $sender_rate - $sender_rate_limit }s
# Keep authenticated users under control
deny
# 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
+ message = Sender rate exceeds $sender_rate_limit \
+ messages per $sender_rate_period
ratelimit = ${lookup {$sender_host_address} \
cdb {DB/ratelimits.cdb} \
{$value} {RATELIMIT} }
git://git.exim.org / exim.git / blobdiff