"bounce" in getmail log

["Russell L. Harris" <rlharris@broadcaster.org>]

I am using getmail4 to retrieve mail and maildrop to sort the
messages.  

I previously discovered that any misconfiguration of the
maildrop configuration file, ".mailfilter", causes getmail to return
with an error and thus causes messages to be bounced.

My getmail log has about a hundred lines of the form: 

2012-01-21 19:11:59 msg 68/125 (8952 bytes) msgid UID260725-1198761243
from <bounce-debian-user=rlharris=broadcaster.org@lists.debian.org>
delivered to MDA_external command maildrop (), deleted

The log reflects only the messages fetched this morning (the computer was
off overnight).

Does "bounce-debian-user" indicate a misconfiguration in my system?

RLH