A switch allowing the class to use ESMTP features (SMTP extensions).
This property is a switch allowing the class to use ESMTP features (SMTP extensions). If this property is true, the class will first send the EHLO greeting to the server and, if that fails, the standard HELO command will be sent.
This property is true by default but may be disabled if it's known in advance that the MailServer doesn't support SMTP extensions.
This property is not available at design time.