How to use third party mail security gateway to scan internal/inter-domain mails

Hi All,

In my mail server environment, there’s a requirement for internal emails (e.g., a mail sent from email address removed for privacy reasons to email address removed for privacy reasons) to be scanned by a third-party email security gateway that the company recently purchased. However, from what I understand, this might be impossible because all internal emails use the implicit Send connector named the intra-organization Send connector.

I would like to know if there is any way to edit or configure the intra-organization Send connector so that, instead of using the intra-organization Send connector, the Exchange On-Premise Server will use my custom/recently created connector. This way, all internal emails will be sent to the third-party email security gateway first, scanned, and have all policies applied before the gateway sends the scanned emails to the recipients within the same domain.

Alternatively, if there is another way to achieve my main goal—using a third-party email security gateway to scan internal emails instead of directly sending them and relying solely on the security of the Exchange Server On-Premise for internal mail protection—please let me know.

Thank you.