1) The user could have been already deleted, but is still bouncing
   from previous distributions

2) specific userid is NOT subscribed, but another (similar or
   very different) userid is and is forwarding.

If you can't figure out the true identify from your logs e.g.,
archive (S * IN listname WHERE SENDER CONTAINS userid),
then it might be useful to turn off AUTO-DELETE for 24 hrs
(or less).


/Pete Weiss