[Mimedefang] Milter failure processing Read and Delivery Receipts

[Kris Deugau]

Michael Sims wrote:
> A properly behaved MUA will send read and delivery receipts (aka
> Message Disposition Notifications) with a null envelope sender.  This
> is required by RFC's 2298 and 2821.  From 2298:
> 
>   The envelope sender address (i.e., SMTP MAIL FROM) of the MDN MUST
>   be null (<>), specifying that no Delivery Status Notification
>   messages or other messages indicating successful or unsuccessful
>   delivery are to be sent in response to an MDN.

This makes sense.  I'll have to see if I can capture some of these to
try to identify them so the legit ones can go through- in the meantime
I'll just turn off that check.  :/

The problem I had is that a few users had installed some sort of
client-side spam filter software that bounced anything that user said
was spam back to the "sender"- with a null sender.  These messages (for
a while, 30-40 per day, from one user) ended up clogging the queue on
our server- in one case IIRC there were 500 or so of these things
waiting to go out.  It caused enough trouble that I started rejecting
these messages if they came from our modems.

-kgd
-- 
"Sendmail administration is not black magic.  There are legitimate
technical reasons why it requires the sacrificing of a live chicken."
   - Unknown