-$Cambridge: exim/doc/doc-txt/NewStuff,v 1.73 2005/09/19 14:01:51 ph10 Exp $
+$Cambridge: exim/doc/doc-txt/NewStuff,v 1.75 2005/09/22 12:58:14 fanf2 Exp $
New Features in Exim
--------------------
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} }