Unable to login to btinternet email via outlook

The error INTERACTIONREQUIRED indicates Outlook cannot complete the sign-in flow and needs the account to be re‑authenticated using the current, supported method.

For consumer mail providers (like btinternet) added to Outlook for Windows, use these steps based on the documented Outlook email setup troubleshooting:

1. Remove and re‑add the btinternet account in classic Outlook profile
   1. Close Outlook.
   2. Open Control Panel → Mail → Email Accounts….
   3. Select the btinternet account (if present) and choose Remove.
   4. Still in Email tab, select New.
   5. Enter name, btinternet email address, and password in the Password and Retype Password boxes, then select Next.
   6. Follow the on‑screen steps to complete setup. Expect to be prompted for the password once more.
   7. When account setup completes, select Finish, then restart Outlook and test sign‑in.
2. If using IMAP and Outlook never prompts for password
   1. When editing the btinternet account’s IMAP settings, ensure Require logon using Secure Password Authentication (SPA) is unchecked.
   2. If Outlook still does not prompt correctly, repeat the Control Panel → Mail → Email Accounts… → New flow above so Outlook can recreate the account with proper authentication.
3. If Outlook is looping or stuck after a crash If Outlook shows repeated sign‑in loops or “something went wrong” after a previous crash, reset the local Outlook state and re‑add the account:
   1. Close Outlook.
   2. Run the New Outlook reset command: olk.exe --clearLocalState.
   3. Start New Outlook again and add the btinternet account from scratch, confirming the server and authentication details during setup.

These steps force Outlook to discard any broken cached sign‑in state and recreate the btinternet account with the correct authentication flow, which resolves typical “Sign in Failed / INTERACTIONREQUIRED” issues when adding non‑Microsoft accounts.

References:

• Troubleshoot Outlook email setup
• New Outlook has stopped working, Fails when starting after 30 to 60 seconds - Microsoft Q&A