Cannot login to the incoming IMAP server

For classic Outlook on Windows, this usually means the desktop app is using the wrong saved password, needs an app password, or is using an IMAP setup option that blocks sign-in. Since the account works on the phone, start with these steps on the desktop:

1. Sign in to the mailbox in webmail first.
   • If webmail does not sign in, the account issue must be fixed with the mail provider or IT admin.
   • If webmail works, continue.
2. If the account is an IMAP account in classic Outlook, make sure Require logon using Secure Password Authentication (SPA) is unchecked during setup.
3. Re-add the account from Control Panel instead of the simplified Outlook prompt:
   • Press the Windows key, type Control Panel, and open it.
   • Select Mail.
   • Select Email Accounts...
   • On the Email tab, select New.
   • Enter the name, email address, and password.
   • Complete the setup wizard.
4. If Outlook keeps prompting for the password or still fails:
   • Verify the username is the full email address.
   • If the password was changed recently with the mail provider, update it in Outlook.
   • If the provider uses app passwords for IMAP, create a new app password in the provider’s web security settings and paste that into Outlook under File > Account Information > select the IMAP account > Account Settings > Server Settings.
5. If the account is Gmail in classic Outlook:
   • During the browser sign-in, the Google permission “Read, compose, send, and permanently delete all your email from Gmail.” must be checked.
   • On Current Channel Version 2412 Build 18324.20168 or later, use the Retry link in the error window to repeat the browser sign-in if that permission was missed.
6. If Outlook reports connection-interrupted errors such as 0x800CCC0F:
   • A bad app password can cause this. Create a new app password with the mail provider and update it in Outlook.
   • On Windows 10, TLS 1.3 can also cause this with some IMAP/POP accounts. Disabling TLS 1.3 is a registry-based workaround and is risky because incorrect registry changes can affect Windows networking and security.
7. If the account still will not add with IMAP and the provider supports POP3, a workaround is to create a new Outlook profile and configure the account as POP3 instead of IMAP.

If the account signs in on webmail and on the phone but not in classic Outlook after these steps, the most likely remaining cause is provider-specific IMAP requirements such as app-password-only sign-in or different server settings.

• Troubleshoot Outlook email setup
• Outlook IMAP or POP server unexpectedly terminated the connection, and the server was interrupted
• Unable to add a Gmail account to classic Outlook
• Authentication fails when you use an IMAP server in Outlook 2016
• NoSuchAccountException: Login Error