21 Sep
2017
21 Sep
'17
4:54 a.m.
My spam filtering is all plan9 based but the ideals are all portable.
Greylisting and delaying a few secs before starting the SMTP
conversation are my most successful filters, After this comes
SPF and using spamhaus to validate the senders IP.
I reject some silly domains like localhost.com and usernames like
user and test.
I also have a list of regexps which match the reverse dns
addresses of adsl blocks which catch many spam bots.
The regexps sound like a lot of work but I have some scripts to
analyse my logs and suggest patterns, so its just a click or two
I can block somthing like:
dhcp.[0-9]+.[0-9]+.[0-9]+.[0-9]+.adsl.nasty-isp.net
-Steve