Emails stopped working in new outlook IMAP

Hi A C

I understand that a third‑party IMAP account stopped working in New Outlook for Windows, and you also can’t add the account again. I am happy to help. Could you confirm:

• Are you on Windows 10 or Windows 11?
• What is the exact error text when adding the account (for example: “couldn’t reach the email server” vs “connection interrupted” vs “you may need an app password”)?

I would love to hear from you soon. Have a nice day!

For IMAP accounts that suddenly stop working in Outlook (including New Outlook), the context shows several common causes and workarounds that can be applied step by step:

1. If using an IMAP account that requires an app password (for example, some Gmail/Yahoo/AOL configurations):
   1. Sign in to the mail provider’s webmail.
   2. Go to Account Information → Security and create a new App Password.
   3. In Outlook, select File → under Account Information choose the IMAP account → Account Settings → Server Settings.
   4. Replace the existing password with the new app password, select Next, then Done.
2. If Outlook shows errors like “The connection to the server was interrupted” or “Your server unexpectedly terminated the connection” on Windows 10:
   1. Open Regedit (Start → type regedit).
   2. Browse to: Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols
   3. If a TLS 1.3 key exists under Protocols, right‑click Protocols and Export first (backup).
   4. Delete the TLS 1.3 key and its subkeys.
   5. Restart Outlook; if sync still fails, restart Windows.
3. If the IMAP server is Yahoo or AOL and messages intermittently disappear/reappear (Mac scenario, but similar IMAP sync issues can occur):
   • On Mac, switching to New Outlook for Mac is the documented workaround: open Outlook and turn on the New Outlook switch.
4. If authentication keeps failing with IMAP and the provider supports POP3, switching protocol can be a workaround (classic Outlook):
   1. Close Outlook.
   2. Open Control Panel → Mail → Show Profiles → Add.
   3. Choose Manual setup or additional server types → Next.
   4. Select POP or IMAP → Next.
   5. Enter account details but set Account Type to POP3 and fill in incoming/outgoing server info from the provider.
   6. Test account settings, then finish and set the new profile as default.

If the problem started recently after Windows or Office updates and only affects IMAP accounts, it may match the TLS 1.3 issue or an app‑password/credential problem; applying the app password update and, on Windows 10, removing TLS 1.3 are the primary documented workarounds.

References:

• Outlook IMAP or POP server unexpectedly terminated the connection, and the server was interrupted
• IMAP Yahoo and AOL accounts might experience issues with re-syncing folder content
• Authentication fails when you use an IMAP server in Outlook 2016