[Mailman-Users] Mailman and recipient spam filtering

Andrew Daviel advax at triumf.ca
Mon Apr 4 20:30:13 EDT 2016

How does mailman handle recipient's spam filtering, if a message gets 
through the mailing list filters but is rejected by a recipient ?

I have an incident where a rejection message was forwarded to a list, 
and on to other members. I don't know if that was even mailman, but it 
got me thinking.

For instance, as a recipient's mailserver, we have various SMTP 
permanent rejection status returns:

550 5.1.1 user is unknown
   - mail will never work and you might as well unsubscribe me
551 5.0.0 Invalid recipient; Use <joe at example.com>
   - if you were really clever you'd auto-update the list membership,
     otherwise might as well unsubscribe me
553 5.3.0 Rejected by CBL
   - sending ip address is listed in a DNSBL and I won't accept mail
     until you get off the blacklist
550 5.7.1 Rejected by SpamAssassin milter
  - this particular message is too spammy (says I won $1M worth of
    viagra, for instance) and I won't accept it, but otherwise it's OK;
    don't unsubscribe me
554 5.7.1 Virus xxx detected by the ClamAV AntiVirus
  - this particular message has a virus or phishing document and I won't
    accept it, but otherwise it's OK;   don't unsubscribe me

which are probably inconsistant, created over a span of many years

Andrew Daviel, TRIUMF, Canada
Tel. +1 (604) 222-7376  (Pacific Time)

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