From a UNIX based system, like Idiom itself, you can issue the command "telnet mail.idiom.com 110" in order to connect. From a Windows based system, which comes with a telnet client much different than UNIX, you will need to set the port to 110 and "local character echo" to "yes" via menus. You may also need to press "ctrl+j" after pressing enter at the end of each line. This should work from any operating system where there is a telnet client.
Here is an example session for the user "foo":
By issuing the "list" command, a list of messages currently in foo's mailbox can be displayed. The number on the left is the message number, while the number on the right is the size of the message in bytes. Since message number one must have been holding up foo's mail, deleting it by issuing the "dele" command along with the message number will allow foo to retrieve further messages.