[Dovecot] Unoffical Survey - What MTA/Spam filtering do you use?

[Tomi Hakala]

Simon Waters wrote:
> Would love to see so serious analysis of "HELO" based blocking. Whilst I tend 
> to think it is a bad idea, if there are criteria I can exploit in identifying 
> things that aren't genuine mail servers -- it fits the strategy.

Some very broken spam tool sends IP address of an MX host it is speaking
to in HELO response, this should never happen with real mail hosts so it
is safe to block all such connections. This blocks high amount of spam
for us.