Verifying an email addressThis morning I was told about a method which can be used to verify a mailing address. Not all mail servers will accept this command as it can be disabled.
This method make use of the SMTP (Simple Mail Transport Protocol) command VRFY (VeRiFY). In the following example, we connect to port 25 (smtp). What I typed is highlighted in bold.
This example shows that the user mike exists but the user xyz doesn’t.
$ telnet somedomain.com smtp Trying aa.bb.cc.dd... Connected to somedomain.com. Escape character is '^]'. 220 somedomain.com ESMTP Sendmail 8.9.3/8.9.3; Fri, 30 Apr 1999 15:00:14 -0700 (PDT) VRFY mike 250 Mike Hoskings <email@example.com> VRFY xyz 550 xyz... User unknown ^] telnet> quit Connection closed.