Password is a String property that represents the authentication credentials used for the IMAP4 account. 

Username and Password are used in the Login method to perform authentication on the remote IMAP4 server when AuthType contains the value atUserPass. Username and Password are used also used when creating SASL challenge / response exchanges using the SASLMechanisms and Capabilities implemented for the remote IMAP4 server. 

Set values in the Username and Password properties prior to calling the the Connect (with automatic login) or Login methods.

Username Connect Login SASLMechanisms Capabilities