If you try to send mail via our SMTP Server (mail.yourdomain.com port 25) just remember it needs SMTP authorization as well as POP3 authorization, and you have to use your mail-box login and password. Please read Help for you local mail program (Microsoft Outlook, or anything else you use).
Also please note that some Internet Service Providers block port 25 connections to any other mail server than their own -- We have an alternate port (tcp 2525) to accommodate people that encounter this problem. Simply change the SMTP port in your mail client from 25 to 2525 if this is the case.
If you are still encountering problems, please open a support ticket with us and we would be glad to help.