Classic Outlook deletes emails from Inbox after a week or so

Henry 20 Reputation points
2026-09-16T15:45:14.2333333+00:00

I know this problem has been posted before, but I have checked all recommended fixes with no luck. This is really bad as I get a LOT of work email and cannot afford to have some missing when I need it. The emails are not permanently deleted -- they are just in the deleted folder. I've checked auto archiving (no archiving checked on folder or mailbox), rules (none that do this), synching (I do not synch with anything online). What am I missing? This started up when the new version of Outlook came out a year or so ago. I stuck with Classic as don't like the new format but perhaps this is designed to force me to change?! Help!

Outlook | Windows | Classic Outlook for Windows | For business
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Answer accepted by question author
Chris-D 1,515 Reputation points Independent Advisor
2026-09-16T16:12:38.2833333+00:00

Hi Henry,

Thank you for sharing the details of your situation.

To assist you more effectively, could you please confirm:

  • Are the affected messages newly received emails, older emails, or replies within the same conversation?
  • Are they moved to Deleted Items immediately or only after some time?
  • What type of email account are you using, such as Microsoft 365/Exchange, Outlook.com, Gmail, IMAP, or POP?
  • Is the same account accessed through webmail, a mobile device, another computer, or another email application?
  • Does this still happen when classic Outlook is completely closed?

In the meantime, please open the Deleted Items folder, select one of the affected messages, and check Home > Ignore. If the option displayed is Stop Ignoring Conversation, the email thread is currently being ignored. Selecting Stop Ignoring Conversation should return the conversation to the Inbox and allow future replies in that thread to be delivered there.

  • You may also check File > Options > Mail > Conversation Clean Up to review where cleaned-up messages are being moved. For now, please avoid running Conversation Clean Up until I determine whether it is related to the issue.
  • User's image

The timing may have coincided with the introduction of new Outlook, but the information currently available is not enough to establish that new Outlook is causing this behavior in classic Outlook.

Please feel free to share the information in the comment below. Once I have it, I'll be better positioned to guide you through the next steps. 

I look forward to hearing your thoughts. 

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  1. Henry 20 Reputation points
    2026-09-16T20:21:03.3366667+00:00

    --I'm using Classic Outlook for MS 365 Version 2608 Build 16.0.20326.20072) 64-bit. I access it on a desktop pc. I do access it occasionally online but that is rare and there is no correlation between doing that and when it happens. I also access outlook on my iphone through its mail app. Perhaps there is a synch issue there and I will check that.

    --Ignore and Conversation Clean Up are not the issue.

    --The affected messages are ones that had been in my inbox for at least several days...probably a week or 10 days or so. It is not simply deleting threads as ones in threads and ones not are both affected.

    --I can't answer you question on whether it happens when Outlook is closed because I don't know when it does it.

    It seems like the most likely source of the problem is my having it on my Iphone. I'll try doing some tests. I appreciate your assistance!! --Henry

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