[Mimedefang] Question about mail/expn/vrfy/etrn

Chris Myers chris at by-design.net
Mon Jul 7 07:28:01 EDT 2003

----- Original Message ----- 
From: "Lucas Albers" <admin at cs.montana.edu>
To: <mimedefang at lists.roaringpenguin.com>
Sent: Sunday, July 06, 2003 12:37 AM
Subject: [Mimedefang] Question about mail/expn/vrfy/etrn

> Under what conditions would a mail server not send the following commands
> on a connection?
> (Assuming I am talking about sendmail.)
> ex:
> s32.iglobalcommunications.com [] did not issue
> MAIL/EXPN/VRFY/ETRN during connection to MTA

You will see this sort of error message when someone connects to your mail
server and then disconnects without attempting to send mail.  It could be
as simple as a network service monitoring program checking the health of
your mail
server.  It could also be someone performing network reconnaisance in a
search for
vulnerable (<8.12.9) sendmail servers.

Sendmail will log that error message if someone disconnects immediately, or
if they
issue a HELO/EHLO command and then disconnects.

Chris Myers
Networks By Design

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