
After you start to create a new rule, you can see the full list of attachment-related conditions by clicking More options > Any attachment under Apply this rule if. You need permissions to do this procedure. For examples, see Use mail flow rules for attachment blocking scenarios in Exchange Online.Īll of these conditions will scan compressed archive attachments.Įxchange Online admins can create mail flow rules in the Exchange admin center (EAC) at Mail flow > Rules.

Check for attachments that exceed a certain size and then notify the sender of the issue, if you choose to prevent the message from being delivered.Check for messages with attachments that can't be inspected and then block the entire message from being sent.Inspect content within attachments and, if there are any keywords you specify, redirect the message to a moderator for approval before it's delivered.Search for files with text that matches a pattern you specify, and add a disclaimer to the end of the message.

Here are some attachment-related tasks you can do by using mail flow rules:

When you inspect attachments, you can then take action on the messages based on the content or characteristics of the attachments. Mail flow rules allow you to examine email attachments as a part of your messaging security and compliance needs. In Exchange Online organizations or standalone Exchange Online Protection (EOP) organizations without Exchange Online mailboxes, you can inspect email attachments by setting up mail flow rules (also known as transport rules).
