function StartAuthenticate(const Challenge, Host, Protocol: string): string; virtual; abstract;
Handles the challenge received from the server in response to the SASL authentication request and returns a response that will be sent to the server.
When the authentication process is started, the SASL server requests initial data for authentication, and StartAuthenticate returns a response to this request.
|•||Challenge - the challenge received from the server in response to the SASL authentication request.|
|•||Host - the hostname of the server where the authentication process runs.|
|•||Protocol - the name of the application procotol that uses SASL, e.g. 'smtp'.|
StartAuthenticate is an abstract method and should be overridden in descendant classes that implement a specific SASL mechanism.