Hi, and thank you for asking your question.
Please carry out the following steps on the iPhone now:
Tap Settings > Mail, Contacts, Calendars, and then tap your email account listed.
Scroll down to the bottom and then tap "Delete account".
Next, go back to Mail, Contacts, Calendars, and then tap the "Add account" option.
Follow the on-screen directions to add your Outlook account one more time; it should work all right now.
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