The most probable reason for this problem is that your Internet Service Provider, router or a software program is blocking the connection between your computer and our servers. To see if this is the cause of the problem, open the default telnet client for your device (please check the operating system manual for your device, for Windows it is “Command Prompt”) and execute the following command:
telnet mail.yourdomain.com 25
If you receive a response similar to “220 mail.yourdomain.com ESMTP”, the problem is not in the connection as you have successfully reached our mail servers, so you will need to double-check your mail settings for typos or other configuration errors.
If the response is different or there is no response from the server, it means something along the way is blocking the connection. You can try changing the “SMTP (Outgoing)” port from the default 25 to port 587 and see if this resolves your problem. If you still cannot connect, please consult with your ISP and/or your local computer technician for further assistance.