A colleague of mine is not fond of backup <acronym title="Mail eXchange">MX</acronym> hosts. He (correctly) points out that all incoming mail should be transmitted through another mail server anyway, so the backup MX hosts only serves as an attack point for spammers.
For the most part I …
I've written a lot of posts about various methods for blocking 

Oops! I guess I'm way behind the times.
This might be a bug with the particular version of Asterisk 1.2 I'm using, but it's pretty darn annoying. Hopefully, it doesn't effect you if you are using the latest version of 1.2 or 1.4.
Note: This is part of a discussion regarding the configuration of a Cisco AS5300 for T.37 Store and Forward Faxing.