> PSUVM.PSU.EDU unable to deliver following mail to recipient(s):
>     <[log in to unmask]>
> PSUVM.PSU.EDU received negative reply:
> 501 Autoregistration Failed, transaction aborted
 
Autoregistration is something that Softswitch Central does.  It's an
email gateway that supports lots of different email systems.  Because
it has to map all addresses into its internal 8x8 scheme, it keeps a
mapping data base.  Autoregistration is automatically creating an entry
in that data base.  Note that both sending and receiving addresses have
to be in the data base.