[Mailman-Users] Rejecting spam at the SMTP level?

[Jayson Smith]

Hello,

I've been running several Mailman lists for the past ten years or so. 
Unfortunately, in recent months some list addresses have fallen into the 
hands of spammers, which is a real headache. Even worse, one particular 
-owner address is receiving nothing but spam, and I don't assume there's 
anything I can do about that without disabling that address for 
legitimate use, as well as for use by Mailman itself.

A few months ago I did some Googling and found a project called 
Mailman-Milter which claims to reject unwanted list mail i.e., nonmember 
postings at the SMTP level. I would love to use this, but there's 
virtually no documentation and I've never been able to get it working. 
Has anyone else had any better luck, or do you know of any other 
solutions? I'm using Sendmail, by the way.

I would set all my lists to just discard nonmember traffic, but I want 
to allow for legitimate users who perhaps don't understand that they 
need to subscribe to lists before posting, legitimate members sending 
from wrong accounts, etc. My current compromise solution is to set my 
lists to hold such messages for moderation, but not send the posters 
messages telling them such, so as to avoid backscatter caused by trying 
to send "You're not a member, your message is being held" messages to 
bogus spammer Email addresses. When I get a held message notice, if it's 
a spammer I discard it and add the address to the discard list, for what 
good that does, and if it's legitimate I reject it, perhaps explaining 
in my own words why the message was rejected, especially if I know the 
person and know they tend to post from the wrong account, etc.

Thanks for any help!

Jayson