In a recent Hanselminutes podcast show "Moving your email into the Cloud" Scott Hanselman and Carl Franklin agreed to do some testing and evaluate the relative merits of Google Apps and Windows Live Custom Domains for email hosting (amongst other things).

In a supporting post on Scott's blog I commented that while Carl Franklin had now abandoned the idea of using Live Custom Domains to host his email (via his own domain name) because we could not find a good way to migrate his legacy emails into his Live Mail account; I felt that there was not neccesarily any good reason to have given up on it.

By using the Outlook Connector it is possible to view both POP3 accounts and Live Hotmail accounts in the same environment and simply drag emails between them.

I know this because (like this guy) I've been doing something similar for years now. Whenever I get an email in Yahoo that I want to be able to access from anywhere, I copy it to a folder in Hotmail (inside of Outlook). Why not just leave it on the POP3 server? well, if I moved it into a folder other than the inbox then I've not found a way to have Outlook download files from anything other than the default inbox folder.

With Hotmail the technology that made this possible was a (presumably) proprietary HTTP (WebDAV?) synchronisation method (because I personally have not seen any other email providers using anything other than POP3). This beauty of this was that it allowed me to manage sub-folders inside of my email account and to be able to see those online (via the web email client interface) as well as 'offline' in Outlook. This was never a very well publicised feature (and Microsoft probably decided that they didn't really want people using it because at one point they threatened to disable it - although it never actually stopped working). It has now been superceded by the Outlook Connector which does pretty much exactly the same thing but also synchronises Contacts to some extent (and Calendar in the paid-for version only).

[I've since Google'd on this and found some useful background info from Omar Shahine]