TF/01 HP/UX build fix: avoid arithmetic on a void pointer.
+TK/01 DKIM Verification: Fix relaxed canon for empty headers w/o
+ whitespace trailer
+
+TF/02 Fix a couple more cases where we did not log the error message
+ when unlink() failed. See also change 4.74-TF/03.
+
+TF/03 Make the exiwhat support code safe for signals. Previously Exim might
+ lock up or crash if it happened to be inside a call to libc when it
+ got a SIGUSR1 from exiwhat.
+
+ The SIGUSR1 handler appends the current process status to the process
+ log which is later printed by exiwhat. It used to use the general
+ purpose logging code to do this, but several functions it calls are
+ not safe for signals.
+
+ The new output code in the SIGUSR1 handler is specific to the process
+ log, and simple enough that it's easy to inspect for signal safety.
+ Removing some special cases also simplifies the general logging code.
+ Removing the spurious timestamps from the process log simplifies
+ exiwhat.
+
+TF/04 Improved ratelimit ACL condition.
+
+ The /noupdate option has been deprecated in favour of /readonly which
+ has clearer semantics. The /leaky, /strict, and /readonly update modes
+ are mutually exclusive. The update mode is no longer included in the
+ database key; it just determines when the database is updated. (This
+ means that when you upgrde Exim will forget old rate measurements.)
+
+ Exim now checks that the per_* options are used with an update mode that
+ makes sense for the current ACL. For example, when Exim is processing a
+ message (e.g. acl_smtp_rcpt or acl_smtp_data, etc.) you can specify
+ per_mail/leaky or per_mail/strict; otherwise (e.g. in acl_smtp_helo) you
+ must specify per_mail/readonly. If you omit the update mode it defaults to
+ /leaky where that makes sense (as before) or /readonly where required.
+
+ The /noupdate option is now undocumented but still supported for
+ backwards compatibility. It is equivalent to /readonly except that in
+ ACLs where /readonly is required you may specify /leaky/noupdate or
+ /strict/noupdate which are treated the same as /readonly.
+
+ A useful new feature is the /count= option. This is a generalization
+ of the per_byte option, so that you can measure the throughput of other
+ aggregate values. For example, the per_byte option is now equivalent
+ to per_mail/count=${if >{0}{$message_size} {0} {$message_size} }.
+
+ The per_rcpt option has been generalized using the /count= mechanism
+ (though it's more complicated than the per_byte equivalence). When it is
+ used in acl_smtp_rcpt, the per_rcpt option adds recipients to the
+ measured rate one at a time; if it is used later (e.g. in acl_smtp_data)
+ or in a non-SMTP ACL it adds all the recipients in one go. (The latter
+ /count=$recipients_count behaviour used to work only in non-SMTP ACLs.)
+ Note that using per_rcpt with a non-readonly update mode in more than
+ one ACL will cause the recipients to be double-counted. (The per_mail
+ and per_byte options don't have this problem.)
+
+ The handling of very low rates has changed slightly. If the computed rate
+ is less than the event's count (usually one) then this event is the first
+ after a long gap. In this case the rate is set to the same as this event's
+ count, so that the first message of a spam run is counted properly.
+
+ The major new feature is a mechanism for counting the rate of unique
+ events. The new per_addr option counts the number of different
+ recipients that someone has sent messages to in the last time period. It
+ behaves like per_rcpt if all the recipient addresses are different, but
+ duplicate recipient addresses do not increase the measured rate. Like
+ the /count= option this is a general mechanism, so the per_addr option
+ is equivalent to per_rcpt/unique=$local_part@$domain. You can, for
+ example, measure the rate that a client uses different sender addresses
+ with the options per_mail/unique=$sender_address. There are further
+ details in the main documentation.
+
Exim version 4.76
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