[Mailman-Users] Question about rejection messages.

Stephen J. Turnbull stephen at xemacs.org
Tue Jul 1 15:24:18 CEST 2014

Robert Heller writes:

 > Comcast is bouncing with the message:
 >     reason: 554 Transaction Failed Spam Message not queued.
 > Is this Comcast's way of 'hiding' the fact that the E-Mail address
 > is no longer valid? That is, does Comcast consider E-Mail to
 > unknown users spam?

How would anybody except a Comcast postmaster know?  If they're doing
something that antisocial, would they admit it publicly?  To diagnose,
I suggest investigating questions like the following:

  - Are other Comcast addresses being accepted for delivery?
  - Is it concentrated on a particular list (vs. there is a subset of
    addresses being bounced that way for all lists)?
  - Are any of them members you recognize as being recently active?
  - Are any Comcast addresses bouncing as non-existent?  (Note that
    RFC 5321 itself gives "no valid recipients" as a reason for a 554
    status return, vs. 550, which is a generic "I can't/won't do that"

If you have strong evidence that it's true (the answers are yes, no,
no, and no), my suggestion is to post to your lists explaining the
situation and your conclusion that such failures mean a non-existent
subscriber, and that to protect your lists from being put on a Comcast
known spammer list, you are disabling/unsubscribing all such addresses
immediately.  Direct those suffering from collateral damage to talk to
their ISP about mending its evil ways (after reinstating them, of

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