HDR From: The Post Office <postmaster>
HDR Sender:	mailer-daemon
SUB Subject: Invalid local real name - or invalid newsgroup

In the following message, it appears from the format of certain
addresses that you have attempted to send a message to somebodys
"Real.Name", or alternatively to an USENET newsgroup.

Unfortunately both lookups have failed.  fullnames -database didn't
contain attempted  Real.Name, nor our copy of active newsgroups 
database did have such a newsgroup.

It is a common mistake to write address alike:   user.host.domain
when you REALLY wanted it to be:                 user@host.domain