On Tue, 13 Jan 2009 09:07:44 EST, Steven Eckard said:
> Good morning, all
> I have had this issue, if it is an issue, before. Is there any practical way
> to tell if these users have aliases causing these errors. I have verified that
> they are not on the list or any way to stop the errors? Thanks.
>
>   1 01/06 01/06 Karen Pitsenbarger <[log in to unmask]>
>                 Last error: 5.1.1 550 5.1.1 User unknown

One failure mode I see fairly often is when address-scraping spamware will
snarf up the name of a list, stick it in the From: field, and then stick
other addresses in the To: field.  If the resulting To: ends up being a
duff address, the bounce goes back to Listserv and ends up in your error
report.

Unfortunately, there's no really good way to tell what *really* happened
other than going through your Listserv console log and finding the timestamp
when the bounce message arrived, take that and look at your MTA logs to find
when the bounce was generated.  Then you have to take *that* info and correlate
that to find the inbound message that bounced, and chase *that* back.