Microsoft is ending linked accounts for its Outlook.com email service, in a bid to thwart hackers and security breaches.
Announcing the changes via the official Outlook Blog site, Microsoft claim "it's a new world" - a far more dangerous one than before it would seem.
Introduced in 2006, linked accounts were a way to quickly switch between different accounts each with their own email address.
But over the next couple months, Microsoft will stop supporting linked accounts and instead help people move to a more robust and secure way of managing multiple email addresses: aliases.
It's a new world
"Why make this change?" asks Eric Doerr, Group Program manager of Microsoft accounts.
"Well, a lot of things have changed since we introduced linked accounts," he says.
"Most importantly, your email address is also often how you sign into the account that is your "digital identity."
"Increasingly, devices allow people to connect their various accounts (Microsoft account, Facebook, Twitter, Apple ID, etc.) to their devices and have it all "just work."
"That means that you want to have one Microsoft account that lets you light up your Microsoft devices and services with your stuff: your gamer score, your email inboxes, your calendars, your people, and your files, as well as to connect to all the networks you care about.
"That's certainly the system we're building, and why we've designed aliases to make it easy to have multiple email addresses (for receiving and sending) connected to a single Microsoft account."
Doeer also believes that linked accounts are "less robust, and less secure than using aliases."
With linked accounts, you can sign in to Outlook.com on the web and then switch to any other linked account without entering a password. But Doeer believes this is where security is at risk…
"Unfortunately, this same feature benefits the bad guys, too," he says.
"We've found that quite often, people who use linked accounts keep their primary account's security info (including password and proofs) up to date, but don't lavish as much care on their secondary accounts.
"It's easier for a malicious party to compromise one of those secondary accounts, which gives them full access to your primary account.
"We believe that aliases provide a more robust and secure capability for managing multiple email addresses."
What you need to do
In the next few days, Microsoft will send an email about this change, including the steps you should take, to everybody currently using linked accounts.
Soon after, when you sign in with a linked account, you'll see a notice with the same info but if you don't use linked accounts, there's nothing you need to do.
In late July, Doeer says Microsoft will begin unlinking linked accounts.
"I know it's a hassle to make changes when you have a setup that works," he says.
"We wouldn't ask you to do this if it wasn't important for your security."
Do you have linked Outlook accounts? How will this change impact you? Tell us your thoughts below