First of all test the sending of mail via the setup and make sure that while you do that, logging is set to maximum.

If the sending fails, then check the logfile for the reason of the failure.

* smtp server down (no response to ping not sending mail : before sending mail to an smtp server, Servers Alive will ping this server, if no response is received then we assume the server to be down and stop sending mail via it.  Via the advanced setup you can disabled this "ping before sending".

* smtp error: T: 16PFalse : Servers Alive tries to connect to the smtp port of the server and this can't be done within the default timeout (of 15 seconds).  You can increase this timeout via a registry setting, check the documentation for the exact registry location.  It could also mean that there is simply no smtp server running on the system you specified as smtp server.

* smtp error: stopped sending mail (rcpt to) error: 550 Relaying denied for name@domain.com: the smtp server is protected against relaying and refuses to send mail to the @domain.com domain.  Your mail server administrator should be able to help you with this.