Why isn t my account syncing with outlook 2016 on windows

At the moment, only personal Microsoft accounts using an Outlook.com domain are able to sync between Microsoft To Do and Outlook 2016. If your personal Microsoft account uses a domain such as @outlook.com, @hotmail.com, @live.com or @msn.com, then your tasks should sync automatically between Microsoft To Do and Outlook 2016 on Windows.

However, if you're using a personal Microsoft account registered to a different domain, like @gmail.com or @yahoo.com, your tasks won't sync automatically. To sync your tasks between Microsoft To Do and Outlook 2016, you'll need to a create a new alias for your account by registering a new outlook.com email address. 

To create a new alias for your account:

1. Sign in to your Microsoft account.

2. Under Account alias(es), select Add email.

3. Select the option to Create a new email address and add it as an alias and enter what you want for your new @outlook.com address.

4. Select Add alias.

5. Once the new alias has been added to your account, just select the option to Make primary.

Now that your new @outlook.com address is the primary alias for your account, you'll need to update your Microsoft account within Outlook 2016:

1. Remove your initial Microsoft account.

2. Head to File > Add Account to add your new @outlook.com email address as a Microsoft 365 account to Outlook 2016.

3. Enter your new @outlook.com email address, then select Connect. (Alternately, you may need to enter your name, email address, and password and then select Next.)

4. If prompted, enter your password and then select OK > Finish.

Your tasks should now sync between Microsoft To Do and Outlook 2016 automatically.