Microsoft is stopping support for a long time feature called linked accounts, which let users manage multiple email accounts (e.g., Hotmail, Live, and Outlook.com) from a primary account after 7 years. According to the company there are a lot of good reasons to have several email addresses, but linked accounts isn’t anymore a trusted feature to manage them all and it’s becoming a target for hackers to exploit. As such within two months, Microsoft will start using Outlook.com aliases as the alternative replacement to manage multiple email addresses.
Starting late July, 2013, Microsoft will start unlinking all accounts, of course that if you don’t use this feature, you don’t have anything to fear. But those folks who have linked accounts, the software maker will be providing the forward and send messages from other addresses features. However, you won’t be able to control more than one account with a single sign-in.
The main reason for the change is because Microsoft has discovered that many users keep their primary email account information (e.g., password) up to date, but secondary accounts don’t share the same attention, and this becomes a security problem that can compromise all the users accounts.
The new change shouldn’t come as a surprise, a couple of months the software maker introduced two-step authentication to make a Microsoft account more secure, but it required to unlink any account linked to a main account.
The company is also working on a functionality called “move an alias” to allow users move an email address and emails from one account to another.
Source Outlook.com blog