Can't reload Outlook on iPhone - IMAP issue

If you're encountering an "invalid IMAP username and password" error when trying to set up your Outlook app on your iPhone, here are a few things to check:

1. Correct Credentials: Ensure that the username and password you are entering are correct. Double-check for any typos or case sensitivity issues.
2. CSV File Format: If you are migrating from another service, ensure that the CSV file format used for the migration is correct. The username and password must be accurately provided in the CSV file for the migration process to access the account.
3. Basic Authentication: If your email provider has disabled Basic authentication for IMAP, you may need to enable it again. This can be done by running specific PowerShell commands if you have administrative access.
4. TLS Version: Make sure your email server supports TLS 1.2 or later, as older versions (TLS 1.0 and 1.1) are deprecated and may cause connectivity issues.
5. Expired TLS Certificate: If your server uses TLS 1.2 but still has issues, check if the TLS certificate is valid and not expired.

If you've verified all these points and still face issues, consider reaching out to your IT administrator or the support team of your email provider for further assistance.

References:

• Can't connect to Outlook by using POP/IMAP and Modern authentication
• "The connection to your mail server timed out" error in Outlook for iOS or Outlook for Android

Hello @Triona Mangan,

Thank you for posting on Microsoft Q&A forum. 

From what you’ve described, it seems you’re encountering an issue with signing in to your IMAP account on the Outlook Mobile App. To help us troubleshoot this effectively, could you please confirm the following:

• Have you previously been able to log in to this IMAP account on Outlook Mobile?
• Does the account work when added to Outlook on your desktop?
• Is email working normally in the service provider workspace? 

Could you also try adding your IMAP account to the native “Mail” app on your iPhone to check if it works there? 

Finally, please provide us the iOS version and the model name of your iPhone device and email service provider of your IMAP account. 

Beside that, could we know which iOS version and the model of your iPhone?

Your feedback on these points will help us move forward with the investigation. We appreciate your cooperation and look forward to your response.