How to Make Other Email Services Available in Google Workspace Settings (Hosts)

First, give the mail server a name on top. You’ll see this name in other email routing settings.

Then select if you’d like to add a single host or multiple ones. 

The multiple hosts option allows you to add more than one mail server for load balancing or in case one of them fails. If you’re adding a single host, simply add the hostname or IP. If you’re not sure what the hostname or IP is, check with your other email service’s support team.

You can try 25, 587. If these don’t work for some reason, try anything between 1024 and 65535 as the port.

You also need to specify the load percentage for multiple hosts, and it must add up to 100%. For example, if you want two primary hosts, enter 50 for each. Alternatively, you can do 60/40, 70/30, and so on.

Then under 2. Options, choose if you want to enable the following: 

Perform MX lookup on host – Deliver to servers associated with the specified domain name. Leave this checked.

Require TLS delivery – Encrypt messages between sending mail servers and receiving mail servers using SSL/TLS. Be careful with this, as emails won’t be delivered if one of the servers doesn’t support SSL/TLS.

Require CA signed certificate – Require a certificate signed by a CA (Certificate Authority) for the mail route. Don’t enable if you’re not sure about this.

Click SAVE to add the mail server. It may take a bit before you can add it in mail routing settings.