Appropriate use of x-loop header?

I'm currently developing a small program to help me better use my phone which does email, running simple programs like dig and ping. I've heard about a header named "X-Loop" that is supposed to help avoid auto-reply program loops. I think it would be important to include support for it but I'm having trouble finding documentation on how it's supposed to be used. Any pointers? Thanks.

I am using a auto-reply script like this:

* !^FROM_DAEMON
* !^X-Loop: auto-reply-user-44@bauani.org
| (formail -r -I"Precedence: auto-reply" \
-A"X-Loop: auto-reply-user-44@bauani.org" ; \
cat $HOME/message; \
) | $SENDMAIL -oi -t

That mean,
1st Line, Mail from Mailer-daemon ignored
2nd Line, Mail with X-Loop header with value auto-reply-user-44@bauani.org ignored
3rd Line, Adding Header "Precedence: auto-reply" for remote user filter
4th Line, Adding my "X-Loop header" with value auto-reply-user-44@bauani.org

That mean if this auto reply mail come back to me by another auto-reply software, my auto-reply script will ignore this mail and not do any auto-reply. Coz it will understand that this mail was genarated from here...

I hope you will understand the usage of 'X-loop' header ...


Thanks
Ahamed Bauani
http://www.bauani.org/