As a security measure, by default you can’t forward email to external addresses. If you’d like to forward email, edit your outbound spam filter policy first.
Required: You need admin permissions to change outbound spam filter policies. For more info, see admin roles from Microsoft.
- Sign in to Office 365 Security & Compliance.
- Select the arrow to expand Outbound spam filter policy > Edit policy.
- Select Automatic forwarding > On – Forwarding is enabled.
- Select Save. You can now use forwards with external email addresses.