Spam - and how PN can crack it.

[#1]

Quote from: dratdestroyer

Using SQLGrey, Spamassasin with lots of plugins and ClamAV  I get one spam a week from thousands of attempts to send spam.

Come back when you run a mail system involving 22 inbound relays, several outbound relays, and mail delivery of circa 1,000,000 messages a day, for ~200,000+ customers.
Seriously though.  I run my own mail server.  What I run wouldn't scale up to that sort of load, (Twin 8 core Xeon, 16GB memory, 2.5TB storage runnign Cent 5).  You have absolutely no idea what sort of problems a large-scale mail deployment brings.  The sort of environment where one tiny tweak of one OS-level setting can reduce your mail throughput to 50% optimum. 
Hobbyist server administration bears no resemblance to serious corporate administration.
FYI, Plusnet run Exim, DSPAM and ClamAV in their inbound mail platform.  All of it is Open Source.
The biggest problem is that they are trying to provide an individual SPAM filter for 200,000 customers.  Spam filtering just doesn't necessarily work like that.  If I was a pharmacist using Plusnet as my ISP, I would be very unhappy if they were filtering out emails based on my research into Viagra and Cialis. 
B.

[#2]

PLEASE, PLEASE!!
Do not instigate any anti-spam policy, just because AOL or Yahoo use it - indeed that ought to be a good reason for not using it!
Why is it that gmail can achieve a virtually perfect level of spaminess for their users without causing draconion bounces/losses/delays? I understand that gmail do send spam - but I am not personally aware of it.
I do know that every spammer and his dog has an aol or yahoo reply address.
Think before you act - so far PlusNet has screwed up inbound email twice (to my knowledge) - don't make it happen a third time!

[#3]

axisoevil:

Quote

I do know that every spammer and his dog has an aol or yahoo reply address.

That is the whole point - they have AOL or Yahoo as their reply address, but they actually come from domains in Poland, China etc.
These systems are specifically designed to stop them.