> 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.