If you use Outlook together with Outlook, Hotmail, Live or MSN mail, you need to re-connect

Quick reminder to those (me included) who use Microsoft email accounts ending with domains "@outlook.com", "@hotmail.com", "@live.com" or "@msn.com". If you are using Outlook 2013 or 2016 to connect to these accounts, you will need to re-create your mail profile and let Outlook download your mail again.

For more details, check the instruction page provided by Microsoft. I just did reconnection to my three different accounts, and it's very simple in Outlook, and took less than five minutes. So, if you've been contemplating on when to do this, now is a great time.