In classic Outlook, messages that seem to “keep coming back” after being read are often related to how the account is synchronized, especially when it is set up as an IMAP account.
There is a documented issue for IMAP-configured accounts where, after reading messages, they can appear to disappear or reappear unexpectedly. This behavior was traced to a problem on the mail provider’s side (for example, Yahoo). The provider has reported that the root cause was identified and a fix has been deployed. If the account uses such a provider and messages still behave oddly (reappearing as unread, re-downloading, or not staying in the expected state), the next step is to check the provider’s current support or status information and, if needed, contact the provider’s support.
If the account is not with that provider, or the issue continues despite the reported fix, review the account type in Outlook (File → Account Settings) to confirm whether it is IMAP, and then:
- Check for any sync-related issues (for example, folders not updating correctly).
- Consider recreating the Outlook profile so that Outlook rebuilds its local view of the mailbox.
- If the problem persists, contact the email service provider, as similar server-side issues can cause messages to repeatedly resync.
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