General

Access control	Messages blocked by an access control policy. This applies only to customers that have been asked to implement access controls by Forcepoint Email Security Cloud operations.
Operational	Messages blocked by controls set up by Forcepoint Email Security Cloud operations in response to a virus outbreak.
Message loop	Messages stopped automatically because they are part of a message loop caused by auto-forwarding or auto-replying.
System	Messages that could not be processed, for example, messages that contravene email protocols.