Question : Internal domain spoofing

Hello,
We are having a problem with email spoofs that are coming from addresses that do not exist but are using our domain.  For example we are getting '[email protected]' being sent to '[email protected]'.  All of my spam filters are on and we are using Trend Scanmail.  Anything I can configure in Exchange to stop these?  We are using Exchange 2007 SP1.
Thanks,

Answer : Internal domain spoofing

Yes, the PTR is not a good item to have in your SPF record, so please get rid of it.

You can test your spf record here:

http://www.kitterman.com/spf/validate.html