I have seen quite a few strange error monitoring reports come from
ListServ the last month or so. Below is one of them:

Err First Last  Address
--- ----- ----- -------
  1 02/03 02/03 [log in to unmask]
                Last error: SMTP; 550 <[log in to unmask]>... User unknown

This looks quite ordinary. However, I know for a fact that this person is
not nor ever was on the list in question. The list is a closed, internal
list. A few other list owners asked me about this same problem. Again,
their lists were closed, internal, and confidential.

For one day that I looked, I did notice that someone sending to one of
these closed lists was put onto the monitoring list. I checked sendmail's
logs, but there was no error message for the owner- alias, and the only
mail passing through the ListServ machine from this person was to the list
itself.

Another strange user is

Err First Last  Address
--- ----- ----- -------
  2 02/07 02/07 [log in to unmask]
                Last error: SMTP; 550 <[log in to unmask]>... User unknown

Anyone seen this before? Any ideas? I can't tell if this is ListServ or
the sendmail m4 definition for the type of machine, which is

OSTYPE(aix4)

These don't happen very frequently, maybe twice a month. Any help is
appreciated. Thanks.

Bob Jackiewicz            UIC Academic Computer Center           [log in to unmask]
University of Illinois at Chicago                            Network Services