Interestingly I can now get this to work, but I have noticed an anomoly, which seems to rely on the strength of the connection (bandwidth).
After making an internet connection; then successfully negotiating through the corproate firewall (via vpn), I click on Inbox. If I have a strong signal strength the prompt (lower left of screen) says 'Connecting' and 'Logging on', then it shows 'Sending and Receiving' - and the mail downloads.
If I have a poor connection, the prompt says 'Dialling' and shortly after that I lose the connection.
So it seems to work on and off, depending on the connection. At least that's my primitive explanation for what's happening.

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Crawfz