Test mail flow by validating your connectors in Exchange Online

To validate and troubleshoot mail flow from Microsoft 365 or Office 365 to your organization's email server (also called on-premises server), validate your connectors. You can set up and validate connectors on the connectors page in the Exchange admin center (EAC). The built-in validation tests that your mail flow from Microsoft 365 or Office 365 reaches:

• Your organization's email server

• A partner organization.

For more information, see Validate connectors

Mail flow issues can also happen when your MX record is not setup correctly. To verify your MX record, see Find and fix issues after adding your domain or DNS records.

Configure mail flow using connectors

Set up connectors to route mail between Microsoft 365 or Office 365 and your own email servers

Validate connectors

When do I need a connector?