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Set up email forwarding from Microsoft 365

Use an Exchange Online mail flow rule (also called a transport rule) to forward Microsoft 365 mailboxes to message.com. Supports user mailboxes, shared mailboxes, and distribution groups.

Mail flow rules are the recommended path. Per-user automatic forwarding is blocked by default on most Microsoft 365 tenants by the Anti-spam outbound policy, and unblocking it is broader than you usually want.

1. Get your inbound address

  1. Open app.message.com.
  2. Go to Settings → Tickets → Inbound.
  3. Click Create inbound address. Pick a local part (e.g., support).
  4. Copy the generated address (e.g., [email protected]).

2. Open the Exchange admin center

  1. Sign in at admin.exchange.microsoft.com as an Exchange Administrator or Global Administrator.
  2. Go to Mail flow → Rules.
  3. Click + Add a rule → Create a new rule.

3. Configure the rule

  1. Name: Forward support@ to message.com.
  2. Apply this rule if: The recipient address matches → add [email protected].
  3. Do the following: choose one of:
    • Redirect the message to → external email → your message.com inbound address. (Single-delivery.)
    • BCC the message to → external email → your message.com inbound address. (Dual-delivery; original mailbox still gets the message.)
  4. Leave the rest at defaults.
  5. Click Save.

4. Enable the rule

  1. Find your new rule in the list.
  2. Toggle Enabled to On.
  3. Exchange Online activates the rule within a few minutes.

5. Verify

  1. From an external account, send a test message to [email protected].
  2. Within a minute, a new conversation appears in app.message.com.
  3. The visitor record shows the original sender, not the Exchange mailbox.
  4. Reply from message.com. The reply lands in the sender's inbox.

Common pitfalls

  • External recipient blocked. Some tenants restrict Redirect to external recipient. Switch to BCC or add an exception in the outbound anti-spam policy.
  • Auto-forward blocked by anti-phishing. If you see policy rejections in the trace logs, check Threat policies → Anti-spam → Outbound and allow forwarding for this rule.
  • Shared mailboxes. Mail flow rules apply to shared mailboxes too. No special setup.
  • Distribution groups. If support@ is a distribution group, the rule fires on the group address. Members continue receiving as before.
  • Message Trace. If anything misbehaves, use Mail flow → Message trace to follow the journey of one email. Faster than guessing.

Next steps