Thanks for your input Yastiandrie.
I'll make no apologies for not knowing the ins and outs of Exchanged/MAPI protocols. After all, this is why I'm here asking for help - because I don't know everything. If indeed EAS/MAPI was the reason why I could see all of my sent emails on webmail on the live.com server then surely it has EVERYTHING to do with the capability of the new Telstra server? Because this is supposed to be an upgrade - I wasn't asked to migrate and I wasn't told that the new service would provide less functionality.
It does appear that the reason I can't do as I did before the 'upgrade' has been explained. Now, as before, I would like a solution. If there is no solution, I would like said email address to be migrated back to live.com.
Thanks.