6.10 Block Outbound Messages Not From Your Domain

A policy can be created to prevent messages from leaving your domain that are claiming to be from another domain, if a mailbox in your domain is compromised. Adding an email filter that allows only messages coming from your domain to leave the system prevents someone from sending emails from your domain while claiming to be from another domain.

  1. Create an outbound message policy, and set it to the top of the list so it activates first.

  2. Add an Email Address filter.

  3. Invert the node logic.

  4. Enable Scan sender address

  5. Enter your domain as the search criteria with a leading wild-card. For example, *company.com.

  6. Connect the filter to a Message Block service.