Using New Outlook on Windows for professional communication and productivity
Dear Mary Yates,
Since the account worked previously and only began failing about a week ago, this may be related to a recent Outlook update, changes in your email provider's authentication requirements, or corruption in Outlook's credential storage.
You can try the following troubleshooting steps:
1/ Remove the affected IMAP account from New Outlook and add it again. When prompted, choose any option to remember or save credentials.
2/ Completely clear the stored credentials:
Close Outlook > Open Credential Manager in Windows > Under Windows Credentials, remove any entries related to Outlook, Office, Microsoft 365, or the affected mail server > Reopen Outlook and add the account again. For reference, please refer to Credential Manager in Windows
Moreover, even if credentials are cleared, authentication tokens may still be corrupted. Please try the following:
- Close Outlook completely
- Press Win + R, type: %localappdata%\Microsoft\Office\16.0\Licensing
- Delete everything inside that folder
- Then go to: %localappdata%\Microsoft\Outlook
- Delete the .ost file (this will rebuild automatically)
- Restart your PC, open Outlook, and sign in again.
3/ Check Windows Account Connections
Open: Settings > Accounts > Review: Email & accounts and Access work or school > Look for an old, duplicated, or disconnected account
4/ If you’re running VPNs, proxy servers, or third-party security applications, they might be interfering with Outlook’s connection to your email server.
Additionally, ensure Outlook and Windows are fully updated. Several authentication-related fixes have been released through Outlook updates.
If the issue persists, to better narrow down the cause, could you provide:
- Who hosts the mailbox (Gmail, GoDaddy, cPanel, IONOS, Bluehost, private mail server, etc.)?
- Does the issue affect all users or only one account?
- Are you able to access the same mailbox successfully through webmail or another email client?
- Have you tested the affected IMAP account on another device or a different IMAP account in New Outlook on the affected device? If so, does it work normally or show the same behavior?
I hope the information shared is helpful. If you have any questions, please feel free to reach out. I'm looking forward to your update.