The administration and maintenance of Microsoft Exchange Server to ensure secure, reliable, and efficient email and collaboration services across an organization.
Hi @Ian Maxwell
Thanks for reaching out to the Microsoft Q&A forum.
Based on your description, it appears that your Exchange account is an Exchange Online account.
In this case, when adding the account in Internet Accounts, I strongly recommend selecting Sign in instead of Configure manually. I tested this on my device and was able to add the account successfully using the Sign in option.
To add your Exchange account to the iOS Mail app, please follow the steps outlined in the following Microsoft Support article: Set up an Outlook account on the iOS Mail app - Microsoft Support
Additionally, please verify that your mailbox is still working properly by signing in to Outlook on the web at: https://outlook.cloud.microsoft/mail/
This will help confirm that the account is active and functioning as expected.
I hope this provides some helpful insight. If you have any updates or further questions, please feel free to reach out
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