The Messaging Gateway (SMG) Disarm feature which strips active content from a number of common file types is stripping active content and some fonts from some PDF attachments even though PDF is not enabled as a attachment type eligible for Disarm on the Malware > Scan Settings > Disarm page. This is not generally harmful but in some cases can result in PDF attachments having all font data stripped making the file illegible.
If a message contains both a PDF attachment and another attachment which is eligible for Disarm, Disarm is applied to the PDF attachment as well. Messages with a PDF affachment but no other Disarm eligible attachment are not processed by Disarm.
Messaging Gateway 10.6.3 and later
This is a known issue and will be addressed with a future release.
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Currently the only workaround for this issue is to enable Disarm for PDF attachments and then deselect all content categories under PDF. PDF attachments will be processed by Disarm but will have minimal action taken against them.
Please see HOWTO93096 for more information on configuring message filtering with Disarm