When a FortiMail unit operates in transparent mode, you can configure one or more of its network interfaces to act as a Layer 2 bridge, without IP addresses of their own. However, the FortiMail unit must have an IP address for administrators to configure it through a network connection rather than a local console. The management IP address enables administrators to connect to the FortiMail unit through port1 or other network ports, even when they are currently bridging.

By default, the management IP address is indirectly bound to port1 through the bridge. If other network interfaces are also included in the bridge with port1, you can configure the FortiMail unit to respond to connections to the management IP address that arrive on those other network interfaces. For more information, see “Do not associate with management IP”.

Unless you configured an override server IP address, FortiMail units uses this IP address to connect to the FortiGuard Distribution Network (FDN). Depending on your network topology, the management IP may be a private network address. In this case, it is not routable from the FDN and is unsuitable for use as the destination IP address of push update connections from the FDN. For push updates to function correctly, you must configure an override server. For details, see “Configuring push updates”.

You can access the web UI, FortiMail webmail, and the per-recipient quarantines remotely using the management IP address.