Bouncing Mail w/KMail fails.

I am using SuSE 7.3 Pro and KDE 2.2.1 and am experimenting with trying to bounce some mail. I know that the e-mail address exists and functions. I am trying to bounce to my wife's account just to test it ;-)) I get the following message that reads in part: "Sending failed: a SMTP error occurred. Command: DATA Response: 550 Error: Message content rejected The following transport protocol was used: smtp://smtp.cbn.net.id:25" I think that my ISP is blocking me from doing this. Is there a work around? Cheers, Brian