If you believe your mail server details are correct, we recommend checking the external connection using Telnet.
To install Telnet using Command Line:
Open a command prompt window. Click Start, type cmd in the Start Search box, and then press ENTER.
Type the following command:
If the User Account Control dialog box appears, confirm that the action it displays is what you want, and then click Continue.
When the command prompt appears again, the installation is complete.
Once Telnet is installed;
1. Click Start, type cmd in the Start Search box, and then press ENTER
2. Type Telnet mail.[yourserverdetails] [portnumber] and click Enter