Policy Way
Securty / Defender Admin Portal Email and Collaboration > Policies and rules Threat Policies > Anti-Spam Policies > Anti-Spam Outbound
Edit protection settings Change forwarding rules to On - Forwarding is enabled.
To allow for Specific users, create new policy, specify who, set same rule.
Save.
Weird Connector Way (unverified)
Create a new connector
Use of connector set to
- Use only when I have a transport rule set up that redirects messages to this connector. Routing set to the same
Create a rule Apply if the sender is in organisation
Do the following redirect the message to the follow connector (above)
Except if The sender is (whoever you want to send externally)