Handling External Disclaimer Exceptions for Trusted Application Relays in Exchange Hybrid
In Exchange Hybrid environments, it is common to use mail flow rules to add an external disclaimer or warning banner to messages received from outside the organization. A typical warning may look like this: WARNING: This email originated from outside the organization. Do not click links or open attachments unless you recognize the sender. This is a good security control. It helps users identify messages that came from external sources. However, there are some scenarios where messages generated by internal application servers may also receive this external disclaimer. This usually happens when an internal application server submits email anonymously to Exchange Server on-premises, and Exchange then routes the message to Exchange Online. In this article, we will look at how to handle this scenario safely by using a custom header…
