Verifying a successful Defend deployment is straightforward and requires checking Microsoft Exchange Online to ensure that the associated rules, connectors, and accepted domains have been added. By default, all rules are enabled on creation:

• Check that the transport rules, connectors, and groups for Defend are present.
• Check that Defend is listed as an accepted domain.

Once complete and the rules are enabled, test messages can be sent to members of the Defend user group.

• Check that the default "External" banner is added as expected.
• Check that the "External" banner is removed when replying to the test message.

Scope of Defects and Rollback

Defend scopes the conditions of any rules directly affecting mail flow to only apply to a distribution group like "Defend_Users". By default, the group will remain empty until the exchange admin adds users to the groups.

Should any configuration defects be discovered, the transport rules can be disabled in Microsoft Exchange Online, or users can be removed from the Microsoft 365 Defend user group.