The most probable reason is that your Internet Service Provider, router or a program is blocking the connection between your computer and our servers. To see if this is the problem, open the default telnet client of your device (please check the operating system manual of your device, for Windows it is “Command Prompt”) and execute the following command for POP3:
telnet mail.yourdomain.com 110
Execute this command for IMAP:
telnet mail.yourdomain.com 143
If you receive a response similar to “+OK POP3 Ready mail2.yourdomain.com” for POP3 or “* OK IMAP4 Ready mail.yourdomain.com” for IMAP4, the problem is not in the connection as you have successfully reached our 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, this means something along the way is blocking the connection and you will have to consult with your ISP and/or your local computer technician for further assistance.