Messaging operations involves making sure that messaging system users get their messages delivered within the stated service levels. Typically, the most critical area of monitoring is in the queue lengths on the message transfer agent (MTA) process computers. If there are problems in the system, they usually manifest in very lengthy message queues. What you watch varies by the functions performed by the Microsoft Exchange Server computer in question. Typically, in a large organization, Microsoft Exchange Server computers take on specialized roles, such as the following: