For 1&1 IONOS accounts with OfficeBusiness or OfficePremium Plus
Learn how to set up an Office 365 email account on your iPhone or iPad to sync your mail, contacts, calendar, reminders and notes.
Tap Settings on the home screen of your iPhone or iPad.
Select Passwords & Access.
Select Add Account.
Enter your Office 365 email address and a description.
When prompted to Configure Manually or Sign In, select Sign In.
On the Microsoft login page, enter your Office 365 password and tap Sign In.
Your Office 365 email account is now set up and the services you have chosen to synchronize will now begin downloading. Please allow time for all the data to synchronize to your iOS device.