SMTP
VRFY
# Server-side
553-Ambiguous; Possibilities are:
553-Joe Smith %LTjoe.smith@example.com%GT
553-Harry Smith %LTharry.smith@example.com%GT
553 Melvin Smith %LTmelvin.smith@example.com%GT
# Client-side
smtp
SMTP ambiguous VRFY
smtp://%HOSTIP:%SMTPPORT/%TESTNUMBER --mail-rcpt smith
# Verify data after the test has been "shot"
EHLO %TESTNUMBER
VRFY smith
QUIT