Now that Microsoft has announced IMAP support for Outlook.com hosted email accounts, how do I convert my exisitng account in Mac Mail from a POP to an IMAP account.

My account was created initially as a @live.com account (with and @outlook.com alias).  I added my Microsoft hosted account some time ago into Mac Mail and it shows up in the preference pane for that account as a POP account.  The server for my existing account is listed in the preferences as "Windows Live (POP)"

I would like to convert from POP to IMAP and still retain all my existing emails.  I do not wish to create a new IMAP account for my Microsoft hosted email and lose what I have archived over the years. 

I use the version of Mac Mail that came with Mountain Lion for email services.

Thanks in advance for your help

SJA