[Mailman-Users] Questions About Uncaught Bounce Notifications

Mark Sapiro mark at msapiro.net
Wed Jul 17 20:18:59 EDT 2019

On 7/17/19 4:23 PM, David Andrews wrote:
> I run an installation that has over 300 lists.  Normally, for years, I
> received around 300 uncaught bounce notifications a day.  In the past
> couple of months, it has dramatically increased to 3000 to 4000 a day. 
> Some questions:  what causes them? Can they be reduced? Do they hurt
> anything? Toes the increase mean a problem somewhere else?

Most likely (you can tell by looking at them) they are spam sent to the
listname-bounces address. They might also be out of office type
responses sent by non compliant (RFC 5230) vacation programs or replies
to list mail erroneously sent to the envelope sender.

What causes them is any message sent to a listname-bounces address that
is not recognized as a delivery status notification by Mailman's bounce
processing. At this point actual unrecognized DSNs are very rare, but if
the message looks like a DSN and is unrecognized, you can post it here,
and we will try to update the recognizers to recognize it.

You can set a list's Bounce processing ->
bounce_unrecognized_goes_to_list_owner to No to eliminate the notices
from that list, but then you will miss any real bounces which are
unrecognized if there are any.

The only harm is the extra mail to deal with.

The increase is probably due to an increase in spam possibly due to
various listname-bounces addresses getting on more spammers lists.

Mark Sapiro <mark at msapiro.net>        The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan

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