Step 1: Go to Anti-Spam | Status | Monitoring Status. Ensure all three Monitored Servers appear as Operational.
Step 2: Enable Level 2 Logging in order for the UTM to list the full SMTP session, as it will be crucial in analyzing the traffic. Anti-Spam | Advanced | Advanced Settings | Other Settings | Log level: Level 2.
Step 3: Download the "logs:MlfAsgSMTP" shortly after attempting to resend a test inbound email.
Note the following:
Subject of the email
Time and Date
This will allow for easier location of the email within the Log.