Phil,
 
1. postmaster@PSUVAX1 is a valid address.
 
2.  stuff!blah!thing@GATEWAY is  another valid  address, even  though the
   gateway should have  converted it to RFC822. I mean,  we all know it's
   not an RFC822 address. But syntactically, it IS a valid address and we
   can't pretend that it violates any of the rules in any of the RFCs. It
   might be impossible to reply to it, but this is not something LISTSERV
   can determine until it tries to.
 
Eric