One of the most basic, and useful, tools for troubleshooting email systems is a Telnet client.

Unfortunately, since Windows XP, Microsoft do not install the Telnet client into Windows by default, so you may need to install the Telnet client yourself.

To do this, go to Control Panel → Programs and Features.

Choose Turn Windows features on or off in the left pane of the window

Scroll down until you find Telnet Client (note do NOT install “Telnet Server”, that is a security risk, unlike the Telnet Client). Check the box next to Telnet Client and press OK

You will normally not need the original installation disks to do this

To use the Telnet client, go to Start → Run in Windows, and type cmd and press OK

In the command prompt window that appears, type:

Telnet <address of VPOP3 computer> <port number>

For instance, to test the POP3 service (port 110) if VPOP3 is on 192.168.1.1, type:

Telnet 192.168.1.1 110

The response should say something like:

+OK VPOP3 Server Ready <random.text>

Other services you can test this way include SMTP (port 25) and IMAP4 (port 143 - if you are using VPOP3 Enterprise)

For SMTP, the response should say:

220 <host name> VPOP3 ESMTP Server Ready

For IMAP4, the response should say:

• OK VPOP3 IMAP4rev1 Server

If the VPOP3 name is not there, then this may indicate that you have another mail server on the same computer as VPOP3, which is “taking over”. If the response includes error text, then you can search for that text here on the Wiki, or it will be useful information to give when you contact technical support for help.