Milter-greylist

Fredrik Nyberg DC wrote:
> The consumption of virtual memory milter-greylist uses grows constantly
> (currently just under 2GB), however resident memory use is constant.
> This does not seem to be affecting performance. Any thoughts?


It sounds like your greylist database is getting huge. It could be you're
getting flooded with an absurd number of greylist entries, causing heavy memory
usage. Certainly the number of dictionary attacks that are prevalent these days
can cause this.

Things that will reduce the memory load would be:

1) Cut off the dictionary attacks on your system by using sendmail's bad
recipient throttling option (sendmail.mc syntax):

# after 5 invalid recipients, start slowing them down with
# 1 second sleeps. Legit mailservers will wait, but
# dictionary attackers will give up
define(`confBAD_RCPT_THROTTLE',5)

2) using a shorter timeout will cause "one-off" connections to be dumped faster.
This has the risk of causing slow-to-retry systems to never deliver mail.

3) using a shorter autowhite period will cause these entries to be dumped
faster. This will purge addresses that did retry but were only used once.
However, this means that legitimate addresses will get greylisted more often.

4) using the lazyaw option will also greatly reduce the number of entries, at
the expense of making it much easier to get past the greylist.