Some messages that pass through the Symantec Messaging Gateway may end up garbled with high ASCII (eight-bit) characters, or with some extra lines added to the body of the message, when delivered to the recipient mail box.
The message corruption is being caused by a misplaced MIME header which can cause a conflict in the structure meant for rendering the message. This is most often seen with the addition of the SPF check header, which is likely to be pushed into the body of the message when this issue occurs, but it can occur with other headers as well.
This issue has been addressed with the Messaging Gateway 10.6.2 release.
Please see the Messaging Gateway Administration Guide for detailed instructions on how to update the SMG software.