[Tfug] nagios checking smtp is causing errors on postfix of box being checked

[elemint at theriver.com]

We have nagios configured to check postfix on an email server and while 
nagios is happy it checked to see that port 25 is answering it creates 
an error every time on the other box running posfitx, here is the error 
it cuases.

Transcript of session follows.

 Out: 220 domain.com ESMTP Postfix (Debian/GNU)
 In:  HELO nagios.box
 Out: 250 domain.com
 In:  MAIL FROM:
 Out: 501 Syntax: MAIL FROM: <address>
 In:  QUIT
 Out: 221 Bye