Forwarding blocked by Microsoft 365

The mailbox with the rule gets an “Undeliverable” message from Microsoft that says something like:

The code AS(7555) (some bounces show it as 550 5.7.520) is the giveaway. Microsoft 365’s outbound anti-spam policy blocks automatic forwarding to any address outside your company, and it is on by default. Your BidTroller address is outside your company, so every forward is stopped.

Only a Microsoft 365 administrator for your company can change this. At many companies that is your IT company or IT person, not anyone in the office.

• It needs someone with the Security Administrator or Global Administrator role.
• An ordinary login, even one with some admin rights, sees only Review under Email & collaboration in the Defender portal, and no Policies & rules. If that is what you see, you are not the right person. Send this page to whoever manages your Microsoft 365.
• BidTroller can’t change it for you, and never needs a login to your Microsoft 365.

1. Go to the Microsoft Defender portal at security.microsoft.com and sign in with an admin account.
2. Open Email & collaboration → Policies & rules → Threat policies → Anti-spam.
3. Click Create policy and choose Outbound.
4. Give it a name, like “Allow forwarding to BidTroller”.
5. Scope it to the mailboxes that forward bid emails (the users with the BidTroller rule, or a group that holds them). A policy scoped to just those mailboxes is safer than changing the default policy for everyone.
6. Set Automatic forwarding rules to On - Forwarding is enabled.
7. Save the policy.

The change can take up to an hour to start working.

While they are there, ask them to add bidtroller.com to your allowed senders, so sign-in codes and the morning digest aren’t quarantined.

Microsoft’s own instructions: Outbound spam policies and external email forwarding.

• You don’t need to redo the forwarding rule. Once the policy is in place, the same rule starts working.
• Emails that bounced before the fix were not delivered. Forward any recent bids you care about by hand.
• To test, forward one recent bid email by hand, then check the Is it working? box on the Setup page. See Forwarded email isn’t showing up.

Forwarding by hand still works. The policy only blocks automatic rules, so you can open a bid email, click Forward, and send it to your BidTroller address from the Setup page.