Jeebus where to start

I have a web client (a large client).

On this client's website I have a couple of different forms that fire off the form content to a person via email with PHP.

Ive probably written 50+ forms of this nature. I mean stuff like Attachements, HTML formatted mail, Multiple recipients and auto responders and never have problems with them but for this client their exchange filtering is killing delivery of the messages.

The forms work fine - Ive sent the results to about 4 different email addys with no problems so I know its on their end but man these guys need to get their act together (this problem has been onging for 3 weeks )

They just installed a new filtering service for web browsing and email protection I guess it is just working a little too well.