Manage mail flow
Domain 5 - Manage mail flow
This domain tests day-to-day control of message routing and handling: transport rules, connectors, accepted and remote domains, distribution group expansion, moderation, journaling, message trace, and NDR troubleshooting.
Core rules
- Transport rules evaluate conditions and exceptions in priority order; the first matching rule with Stop processing wins. Actions can add disclaimers, redirect, moderate, block, or modify headers.
- A transport rule's From condition matches the header sender, while Sender matches the envelope sender; use the right one for spoofing and delegation scenarios.
- Distribution group expansion happens after transport rules. Moderation routes messages to a moderator before delivery; the moderator can approve or reject.
- Message trace is the primary troubleshooting tool for delivery, transport rules, and connector routing. NDR codes distinguish mailbox-not-found, blocked-sender, and routing failures.
Worked example
Contoso wants an external disclaimer on all mail sent outside the organization except messages from the executive team. Create a transport rule with the condition The recipient is located Outside the organization, add an exception where the sender is a member of the Executives group, and set the action Append a disclaimer with a fallback action to wrap if the message cannot be modified. Reasoning: the exception prevents executive mail from receiving the disclaimer; fallback controls what happens to signed or encrypted messages. Test with internal and external recipients and confirm with message trace.
Traps
- Disclaimers cannot be inserted into some encrypted or signed messages; fallback matters.
- Stop processing on an earlier rule prevents later rules from evaluating.
- Journaling captures messages for compliance but does not replace transport rules for blocking.