Message bouncing back.

Hey, everybody:

I'm concerned that the message header that ForeFront is adding is causing e-mails to be bounced by several of our customers.  It's bouncing 554 Not authorized.  We actually rerouted the e-mail through a smarthost that can successfully send to this domain, but the same message is returned.  

Question: Is it possible to remove the X-ForeFront-AntiSpam-Report header from the e-mail?  

Thanks in advance!