Content Filtering "If message contains attachment" does not match HTML attachments

Products

• Messaging Gateway

Issue/Introduction

Content Filtering policies in Messaging Gateway do not always identify HTML MIME parts as attachments when using the "If message contains Attachment" content filtering condition.

Cause

Messaging Gateway treats HTML message content differently from most attachments and attempts to distinguish between HTML message body content and attached files. HTML data will be treated as an attachment based on the Content-Disposition attribute of the HTML MIME part:

No Content-Disposition attribute	HTML data is treated as message body and not an attachment
Content-Disposition: inline	HTML data is treated as message body and not an attachment
Content-Disposition: attachment	HTML data is treated as an attachment

Resolution

This behavior is by design and applies specifically to HTML message data. Other file types are treated as attachments without distinction.