Carefully check the spelling of the name of your mail server. Find out from your IT/ISP whether the server requires authentication in order to send e-mail. If so, then enter your userid on your mail server and password. Confirm with your IT/ISP the port number the mail server uses to commicate with.
Click on the Test email button. A plain text e-mail is sent using the settings you have entered to the "reply to" email address at the top of the dialog. If there is anything wrong with the settings entered, then the e-mail will fail. It fails because there is something wrong with the settings.
Sorry, that's about all we can say.
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Andrew Bates