For outbound attachment filtering, see Attachment Content Filtering - Outbound.
All messages, except those from exempt senders, go through attachment filtering. Use the Inbound Settings > Content Policies page to specify actions to take on inbound messages if they contain attachments with certain file name patterns or MIME types. If email is sent to a recipient on an allow list, content filtering is bypassed.
Attachment Content Filtering is limited to text type files such as most MS Office files, html, pdf files, and other document files. Note that any file type of size 0 is also ignored by the attachment filter policy.
You can select Archive Files Content with any filter to search the contents of attached archives. Use the Password Protected Archive Filtering feature as follows:
When set to Scan, any email containing a password protected attachment is blocked.
When set to Ignore, your attachment filter policies are applied to any email containing a password protected attachment.
Messages that are blocked due to attachment filtering appear in the Message Log with the word Attachment for the Reason if you click Show Details for the message. For example, if you create a filter to block messages with attachments whose file names match a pattern of word*, the entry in the Message Log would contain:
Action:Blocked Reason:Attachment (word_2010_xml.tgz)
where word_2010_xml.tgz is the attachment file name that caused the message to be blocked.