When some PDF files are scanned by the Disarm feature of Symantec Messaging Gateway, the PDF file size may increase, sometimes dramatically. The increased size of the attachment may cause the email to be rejected by downstream mail servers due to message or attachment size limits.
This issue is likely to only impact a small ratio of PDF files. For those files it does affect, there is no current workaround to this issue.
Symantec is currently investigating this issue. Please subscribe to this article for updates.