First let me describe my setup. I have a virtualised server with one VM for ispCP where I host a bunch of websites. Email for these websites is hosted through Google Apps.
The problem I have is that if I try to send an email from this server (such as from a PHP contact form) to one of the Google Apps email accounts it never arrives but it does arrive if I send it to an email address that does not have a website on the server (e.g. a GMX account).
Looking around, this problem seems to be caused by emails being routed internally. I have looked around but I can't seem to find any simple, clear solution.
I am running on Debian 6 64bit with ispCP and postfix.internal routing postfix