Using Outlook for iOS in business environments for email and scheduling
This thread started on May 23, 2024 which is then continues on Sep 24. The source of the problem may not be the same.
Those who have problem accessing your mailbox after September 16, follow this instructions:
If you use Apple Mail:
Apple Mail supports Modern Authentication by default when you setup the account as Outlook.com. If you use Apple Mail and you are seeing password prompts or connection errors, this is most likely happening because your account got configured as basic authentication. To mitigate the issue, remove the account and add it back as Outlook.com:
- Go to Settings > Mail > Accounts.
- Tap the email account you want to remove from your iPhone, then tap Delete Account. For more information, please go to Add and remove email accounts on iPhone.
Add your account back to Apple Mail:
- Go to Settings > Mail.
- Tap Accounts, then tap Add Account.
- In the Add Account dialog, choose Outlook.com.

If removing and re-adding the account does not address the issue, do the following:
- Remove the account again.
- Go to Settings > Safari, then tap Clear History and Website Data.
- Reboot your iPhone.
- Add the account back and proceed through the Outlook.com account sign in flow.