What’s the difference between internal and external MX records?

Organizations sometimes use different MX records internally versus externally:

External MX: Published in public DNS. Routes mail from the internet to your perimeter mail servers.

Internal MX: Configured in internal DNS (split DNS). Routes mail between internal users directly to internal servers.

Benefits: Internal mail stays on the internal network. Faster and more private.

Risks: Inconsistency between internal and external DNS causes confusion. Authentication testing may produce different results depending on where you test from.

Ensure both internal and external configurations are correct and consistent with authentication records.

Different docking instructions for local harbor traffic versus ships arriving from open sea.