Third-party integrations

Most domains are hosted in one place. Some aren't:

• a company moves half its mailboxes to Microsoft 365 and leaves the rest here
• an anti-spam appliance has to sit in front of the mail server
• a compliance service has to see every outgoing message

These pages cover running your domain here together with such a service, with both sides handling the same domain at the same time.

Every guide here is optional and advanced

With no external provider involved, none of this applies, and the default setup is the right one: mail arrives here, leaves from here, and DNS follows automatically.

Guides

• Microsoft 365 hybrid email. Some mailboxes in Exchange Online, the rest here, on one shared domain. Covers both directions: Microsoft receives mail from the internet first, or this server does.

A setup we don't cover yet has the same shape

A different cloud mailbox provider, a filtering appliance, and an outgoing smarthost all use the same four panel features: third-party mail gateway, relay to your own server, custom DNS records, and sender verification.

The Microsoft guide shows how they fit together, and its reasoning works as a template even when the provider uses different names.