This article provides a summary on how to add new mail domains for Exchange accounts in MachPanel and Send Connector for Internal/External Relay Accepted Domains.
This article applies to MachPanel all version
You can manage "Mail domains" for Exchange account by clicking on the Manage from the following path: Home >> Service Director >> Exchange Hosting >> Exchange Accounts.
Select Mail Domains tab. Enter the new SMTP domain name and select type of the domain and click on Add New Domain button. See the snapshot below:

Enter the new SMTP domain name and select type of the domain and click on Add New Domain button. See the snapshot below:

Set As Primary
On clicking Set as primary you will following pop up from which you can select the desired option.

Add Send Connectors for Internal/External Relay Accepted Domain:
“MachPanel, offer you a complete implementation of Internal / External relay, If you just mark domain as internal / External relay, it will convert it to type internal / external relay, but it will not work until you create a Send Connector specifying where to route emails that are not local to this mailing system.”
Follow following steps in order to add internal/external relay accepted domains.

Now Select type of Relay: a) Internal b). External