Cisco PIX - changes the command letters to 'X' before passing them to the real SMTP server Exim - expn not available variant 550 EXPN not available Exim - vrfy not available variant 252 VRFY not available Exim - vrfy variant 250 <root> is deliverable Exim - not deliverable variant 550 <root> is not deliverable Alt-N MDaemon - vrfy variant 502 command is not active Gordano NTMail - seen this on NTMail 4.30.0012, NTMail 5.06.0016 Sendmail - vrfy variant Symantec Mail Security 504 <foo>: Recipient address rejected: need fully-qualified address Lotus Domino - vrfy variant