Can any of you sendmail gurus help me out?

When I see this entry in my maillog, what are all the possibilities as to why this failure occurred? I understand that it could be a network or protocol failure, but any more specifics or ideas would help.

did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA


Thanks in advance

This is usually due to a monitoring system checking to see if your sendmail service is alive. Are you or someone monitoring your box?

This can also be due to someone scanning the service for exploits. Are you upto date?

I do get that when my provider periodically scans my services. In this case, the error occurs when someone from a particular IP address attempts to send mail to a client on my server. It is an intermittent problem which suggests a network issue, but I'm trying to nail it down to a root cause.

PS - the person sending the mail to my server gets the "server not available" error in their mail client when this happens. I know the connection is being made based on my error logs, but something is getting lost.

Originally posted by jason_s
Can any of you sendmail gurus help me out?

When I see this entry in my maillog, what are all the possibilities as to why this failure occurred? I understand that it could be a network or protocol failure, but any more specifics or ideas would help.

did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA

If you telnet to port 25 on your box, you'll usually see a log message along those lines.