If you are configuring a smart host connection, you will need your mail server's public IP address or hostname.

To find your Microsoft 365 host name, follow the steps below:

1. Log in to your Microsoft 365 admin center.
2. From the navigation panel, select Settings > Domains.
3. Select your domain from the list.
4. At the top of the page, select DNS records.
5. Click the Manage DNS button. When you click this button, you'll be taken to a How do you want to connect your domain? page.
6. Under Add your own DNS records, click More options.
7. Select the Add your own DNS records option.
8. Click the Continue button.
9. Select the Exchange and Exchange Online Protection check box.
10. Click the drop-down arrow next to MX Records. You can find your host name in the Points to address or value column.