Microsoft finally added IMAP support to its free Web e-mail service, Outlook.com. Using IMAP is preferable to POP, because it offers a way to keep your e-mail synchronized when using third-party clients.
You can use Outlook.com with Apple's Mail app on OS X, but its new account wizard is preconfigured to use POP whenever you enter "outlook.com" as your e-mail address. Here's how to set up Mail to use IMAP for Outlook.com instead of POP, so you can take advantage of the new IMAP support.
Step 1: If you're using two-step verification with your Microsoft account, you need to go to https://accounts.live.com/proofs/Manage and create an app password to use. If you're not using two-step verification, move on to Step 2.
Step 2: Launch the Mail app in OS X and start the add account wizard by going to File > Add Account. If you've never used Mail and you're opening it for the first time, the add account wizard will appear automatically.
Step 3: In the address field, enter a bogus e-mail address and leave the password field blank, then click Continue.
Step 4: For incoming mail server settings, make sure that the account type is set to IMAP, then enter "imap-mail.outlook.com" as your incoming mail server. Enter your real Outlook.com e-mail address and password in the username and password fields. Remember to use your app password here if you're using two-step verification. Click Continue to move on to the outgoing mail server settings.
Step 5: Under outgoing mail server, enter "smtp-mail.outlook.com." Check the box to use authentication, then click Continue.
Step 6: At the account summary page, double-check the mail server settings to make sure that everything has been entered correctly. You'll notice that your e-mail address shows up as the bogus address you entered in Step 2. We'll go back and fix this after the account's been created. Make sure to uncheck the box next to "Take account online," then click Create.
Step 7: When the Accounts window appears, select the account you just created from the left pane. When your account information appears, replace the bogus e-mail address with your real Outlook.com e-mail address. When you're all done, close the Accounts window and make sure to save your changes.
Step 8: At the main Mail menu, go to Mailbox and select "Take All Accounts Online."
That's it. Within a few moments, your Outlook.com folders and e-mail messages will show up and be in sync with the Web and mobile clients.