Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
It seemed that I solved my problem by working on the "SSL". Go to the setting in your iOS device, and find Mail. Into the Mail, click on the accounts that relates to the "outlook.office365.com"; then find Advanced and into "SSL", then disable the "USE SSL". Turn off the device and turn it back. Turn the USE SSL back to green if it does not turn on by itself. Otherwise, you would not be able to receive or send emails from that account.
Hope it works to you.
Eric