Please define "process mailbox"
What is "A program"? Some other mail client?
You'll need to provide a whole lot more information. Is this a POP
server? IMAP? Exchange? Is this remote desktop connection by any
chance a machine on the same LAN as the server? Perhaps the mail
server is not accessible from wherever this 'regular HP desktop' is?
To reply via e-mail, remove The Obvious and .invalid from my e-mail address.