Robert Davison wrote:
I'm running the base Sendmail with Mailscanner and SpamAssassin from the ports.A simple question.... I'm installing SPF to help the fight against spam. Which is the most efficient way of doing it.....Sendmail milter or the p5-Mail SpamAssassin plug-in. They both do the same, but is one a better way than the other ?
Ah -- actually there is a crucial difference in the way SpamAssassin
and milter-spf work. SpamAssassin uses the SPF status of a message
to add to the spam score it calculates -- typically, a message which
passes all the SPF checks has an approximately zero result on Spam
scoring, as will a message where there is no SPF stuff available at all;
but one which fails the SPF tests will get about 3 spam points. (Which
means that even a message failing SPF checks can be passed as ham)
milter-spf however operates in a binary fashion -- anything that fails
is rejected, anything that passes is accepted.
In general I prefer the SpamAssassin behaviour -- not all the world has
immediately accepted SPF as a good tool against spam; there are any number
of edge cases where a legitimate message can contradict what the SPF
settings say (mail forwarding is a particular problem) and one of the
groups that has adopted SPF most wholeheartedly are in fact, the Spammers
themselves.
SpamAssassin processing is however much heavier on system resources than
milter-spf.
Cheers,
Matthew
--
Dr Matthew J Seaman MA, D.Phil. 7 Priory Courtyard
Flat 3
PGP: http://www.infracaninophile.co.uk/pgpkey Ramsgate
Kent, CT11 9PW
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