Password is a published property String property in TIdSMTP. Password contains the authentication credentials provided when using the authentication mechanisms for the SMTP client in the Authenticate method. 

Sets the values for the Username and Password properties prior to calling Connect for the SMTP session. 

Username and Password are used, when the authentication type in AuthType contains atDefault, to send the encoded values for the AUTH LOGIN command. Username and Password are also provided for use in the SASLMechanisms supported for the SMTP session. 

DidAuthenticate will contain True when authentication has been successfully performed. 

DidAuthenticate AuthType Authenticate SASLMechanisms Username