Users with POP3 or IMAP accounts who created Outlook.com accounts using their own email address, to sync just their calendar and contacts have noticed a problem after their account was migrated to the new server and opened in Outlook 2016: all replies use the Outlook.com account, not the account that downloaded the message.
Custom Domains are once again available in Outlook.com.
How to change the Outlook.com or Exchange filename (usually your email address) in the Navigation pane in Outlook 2016.
How to change the account name for Outlook.com and Exchange accounts in Outlook 2016 when the account name field is not editable.
How to remove (the new) Outlook 2013 and 2016 Add-ins from Exchange online and Outlook.com accounts.
An Office 365 user complained that he couldn't use backspace in Outlook on the web when he opened his account in Microsoft Edge. (Both Exchange online and Outlook.com after affected, although only a small subset of users of either service have this issue.) Users with problem can choose from one of two workarounds to fix
Sharing Outlook.com Calendars with other family members
How to create an Outlook.com alias to use to log into Outlook on the desktop when your Microsoft account uses a non-Microsoft email address.
Live Mail will no longer sync calendar and contacts with Outlook.com after the account is migrated to the new server. You will be able to use it for email, using IMAP (preferred) or POP3.
How to block email from specific domains in Outlook.com using a rule.