Outlook reloading old messages as unread

@Sheila Hart said

Outlook is suddenly repeatedly loading in the same old messages

If this is for a Microsoft Hosted email account (e.g. outlook.com, hotmail.com) what do you see if you access your account using Outlook Web? https://outlook.cloud.microsoft/

For a non-Microsoft account, what do you see if you use the mail web interface for that email provider?

If Outlook Web/Web Mail looks right, then it could be a problem with the New Outlook for Windows local cache. You can try Nuking your New Outlook for Windows Profile. Sometimes this will clear out the bad data.

See the answer by "Hornblower409 Dec 11, 2025" in
https://learn.microsoft.com/en-us/answers/questions/5655980/outlook-starting-error-repair-reinstall-reset-does

Deletes all local configuration files and cache. Resets the application to a first-run state. You will have to add back all of your email accounts. (Does not touch your email account data. e.g. email, contacts, calendar).

Hi. I'm Brian and I'll try to help.

This forum is dedicated to issues with new Outlook for Windows. Is that what you're using? Who is your mail provider and what type of account (POP, IMAP, Exchange) are you using? If you are using Outlook.com for your mailbox, this is an ongoing problem of which Microsoft is aware.