Having problems sending mail through your own SMTP server?

First, you can test your SMTP server by using the following service:

http://www.mxtoolbox.com/diagnostic.aspx

And typing in your SMTP server address, such as "smtp.domain.com". This will confirm that your SMTP server exists and is running. It was also check that your SMTP server is not an open relay (i.e. anyone can use it to send spam).

The next step is to see if your ISP is blocking SMTP traffic. To do this, go to Start > Run and type in "cmd" then press return.

A black box should then open. Type in "telnet smtp.domain.com 25" and press return.

If successful, after a few seconds you should see "220 smtp.domain.com ESMTP". If not*, then you need to speak to your ISP about unblocking the SMTP traffic. Alternatively you could try sending SMTP traffic using a different port. For example, Webtechy also provides SMTP traffic on ports 225 and 587 which may not be blocked by your ISP.

* A common error is "Could not open connection to the host, on port 25: Connect Failed".