Boolean - True on success.

Authenticate is a Boolean function that performs account authentication on the SMTP server. Authenticate returns True when successful, or False if authentication failed. 

You must specify the AuthType before calling the Authenticate method. Authenticate should be called only once for a SMTP session. 

Send will call Authenticate before transmission of an E-Mail message, if the SMTP session has not already been authenticated. 

When AuthType is atSASL, Authenticate checks to ensure that SASLMechanisms contains a valid authentication mechanism for the server.