1) Access the Exchange Admin Center
Navigate to the Exchange Admin Center, then go to Mail flow → Connectors.
2) Add a New Connector
Click Add a connector.
3) Select Connector Direction
Choose the following options:
From: Partner organization
To: Office 365
4) Name the Connector
Enter a descriptive name, for example: Mailsecure Cyfox – Inbound.
5) Configure Sender Verification
Select By verifying the sender IP address, and add your relay’s public IP addresses.
6) Adjust Security Restrictions
Under Security restrictions, uncheck Always use TLS, and allow connections without TLS.
7) Review and Create
Review the configuration details, then click Create connector to finalize the setup.