Hmm.....I'm clearly making some fundamental mistake here! Please bear with me as I try to explain my problem:
To test your method, I created an email account on EMBC and sent and received a few emails just to populate it a bit.
I then created a matching account on Outlook (2010). The emails synch'd and Outlook showed the emails as you would expect.
I found the .PST file and backed it up
I created an email account on my own personal web site.
I created a matching account for that on Outlook and of course it was empty.
I copied the .PST file from the original EMBC account and replaced the empty one with it.
Outlook synch'd again and immediately all the emails disappeared!
What am I missing??