How to rename your Microsoft account
Back when Microsoft launched the email service outlook.com publicly it shipped with a feature to rename your Microsoft / Windows Live account. I unknowingly did so at that time and switched from a custom email address to an outlook.com address. Microsoft quickly removed the feature again from its website, reportedly because it was causing issues for users who did rename their accounts. Some users reported that they were unable to access old emails, files they hosted on SkyDrive and other data that was available under the old account.
Microsoft seems to have resolved those issues as the account renaming functionality has been re-enabled in the Microsoft account control panel.
Before we look at that in detail, I'd like to spend a paragraph listing some of the reasons why you may want to rename your email address. The most obvious reason in my opinion is the selection of a new username. Maybe you want to change your old username to a different one because you find it no longer appropriate and do not want to use it anymore when you are sending emails.
Another reason may be that you want to switch to a different address away from one of the domain names that Microsoft is making available (outlook.com, hotmail.com, live.com and maybe local domains like hotmail.de).
To change your Microsoft account visit the following page on the live website. Here you have the option to create a new email address using one of Microsoft's domain names, or use a different address for the account.
Microsoft notes that the account information and data do not change and that it may take up to 48 hours before everything is switched to the new address.
Note that you will receive a confirmation email if you are selecting a different address. Microsoft displays the old and new account name in it, as well as options that you can undertake to change your password and rename your account again to the old address.
You may receive a verification email on top of that to verify the new email address that you have selected for your account.
But what about emails that are sent to the old address? Microsoft displays a prompt when you first log in with your new email address that asks you where you want those emails to be saved to. They are not lost by any means. Just select a new folder or an existing one and use the email service just like before.
If you have used the email that you want to rename to set up your Windows Phone account, you need to consider the following: Features on the phone that are linked to the address, SkyDrive, Xbox Live, Marketplace or email may stop working. To use those features again, you need to restore it to its factory defaults which unfortunately erases all personal contents in the process.
Microsoft recommends setting up an alias instead and use it to send and receive emails without changing the address and affecting phone settings.
You may also want to check out the following renaming FAQ that answers several other important questions that you may have.