Inbound, outbound, and internal mail

PureMessage for Microsoft Exchange uses the configured mail domains, trusted relays and IP address of the connecting host to distinguish between inbound, outbound, and internal mail.

Inbound mail

The message is inbound if either of the following criteria is met:

  • The recipient domain is on the configured domain list and the sender IP address is external.
  • The recipient domain is on the configured domain list and the message comes from an internal IP address that is on the list of upstream (trusted) relays.

Outbound mail

The message is outbound if the recipient domain is not on the configured domain list.

Internal mail

The message is internal if the recipient domain is on the configured mail domain list and the sender IP address is internal or unavailable (in the case of internal MAPI message submission by Microsoft Outlook).