AuthType is a TIdIMAP4AuthenticationType property that indicates the mechanism to use when performing authentication for the IMAP4 client connection in the Login method. 

When AuthType contains the value atUserPass, the values in the Username and Password properties are used to perform authentication. Username is required. Password may contain an empty string ('') if the IMAP4 acccount does not require authentication credentials. 

When AuthType contains the value atSASL, the authentication mechanisms found in the SASLMechanism and Capabilities properties are used to send the AUTHENTICATE command. 

AuthType is used in the Login method following TLS handshaking and negotiations when UseTLS contains True, and the value in LastCmdResult contains the value IMAP_OK. 

The default value for AuthType is DEF_IMAP4_AUTH, as assigned during initialization of the component. 

Use Login to establish and authenticate the IMAP4 client connection. 

Use ConnectionState to determine the state of the IMAP4 connection following authentication or completion of the Login method. 

Use Capability to request and populate the Capabilities supported on the remote server.

Capabilities Capability ConnectionState Login SASLMechanisms UseTLS