State is a TIdPOP3ServerState property that represents the POP3 state for the client session. State is updated by various event handlers during the lifetime of the threaded client connection. 

When the client connection is established, State is set to Auth and the session enters the AUTHORIZATION state. In this state, the client must identify itself to the POP3 server to gain access to the associated maildrop. 

When the client is successfully authorized, the client session enters the the TRANSACTION state, and State is set to Trans. In this state, the client requests actions on the maildrop on the POP3 server. 

When the client has issued the QUIT command, the session enters the UPDATE state and STate is set to Update. In this state, the POP3 server releases any resources acquired during the TRANSACTION state and says goodbye. The client connection is then closed.

TIdPOP3ServerState