[afnog] spam filter for smtp

[Chris Wilson]

Hi Ismail,

On Tue, 15 Jun 2010, Ismail M. Settenda wrote:

> The thing with greylisting is I failed to auto add sites like google and 
> yahoo who use and keep changing outgoing servers to balance load (cant 
> find the url with the how-to).
> 
> I then had to keep manually adding these smtp servers and couldnt keep 
> up the pace and was also tedious...thus the move to policyd-weight which 
> also blocks alot more stuff before it hits postfix or amavis and thus 
> improves processing of emails as well.

Firstly, you don't have to add them at all. They will pass greylisting. So 
some emails from Google and Yahoo get delayed by 15 minutes. Big deal.

Secondly, you could join Jaco Kroon's distributed greylist to share the 
work of learning these servers across many sites and emails:

  http://www.mail-archive.com/exim-users@exim.org/msg33805.html

Thirdly, I get just as good results from rejecting bogus or dynamic HELOs 
as I do from greylisting, so you could drop greylisting entirely.

For more information, check out my presentation:

  http://www.exim-new-users.co.uk/Chris-Wilson-Aptivate-Reducing-Spam.pdf

Cheers, Chris.
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