Most likely the mailer on the 3 systems below is forwarding
mail to another for the users, and the forwarding address is bad.
>     Can someone explain the following?   Here are the names and
> addresses of people subscribed to my list.  They subscribed themselves
> so I presume the addresses are correct and legitimate.
>
>
> [log in to unmask]              James Barnes, Jr.
> [log in to unmask]             Barbara Semonche
> [log in to unmask]              karen c blansfield
>
> -----------------
>
>        Here are the error messages I have been getting from the mailer
> and PSU:
>
>
> PSUVM.PSU.EDU unable to deliver following mail to recipient(s):
>     <barnes@tipper<.oit.unc.edu>
> PSUVM.PSU.EDU received negative reply:
> 550 <[log in to unmask]>... User unknown
>
> PSUVM.PSU.EDU unable to deliver following mail to recipient(s):
>     <[log in to unmask]>
> PSUVM.PSU.EDU received negative reply:
> 550 <[log in to unmask]>... User unknown
>
>            ** TextConnected to tipper.oit.unc.edu:
> >>> RCPT To:<[log in to unmask]>
> <<< 550 <[log in to unmask]>... User unknown
> 550 karen@gibbs.oit.unc.edu... User unknown
>
>      Why is the mailer attempting to deliver to a wrong address? Surely
> if there have been changes at the site they should have been aliased
> so that the list would not get such bounces needlessly?