New Outlook Emails Disappearing

Question

New Outlook Emails Disappearing

Matthew Henrich 0

I've been using new outlook for a while now and I find that my emails will randomly disappear and reappear. Once a week I sift through my emails and sort them in to folders to keep my main inbox clean. I did this on Friday, inbox was nice and clean. I log in on Monday and like 30 emails showed up in my inbox that weren't there when I was sorting on Friday. These emails were from about 2-3 weeks ago.

I had to stop using the flag feature for this same reason. I would flag an email that I wanted to come back to, and the email would disappear over time, and also disappear from my flagged list. Never had this problem with old outlook, I could have flagged emails in my list for years and they would never disappear.

Is there possibly a setting I have set wrong somewhere? Or is this a known issue?

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2 answers

Your answer

Answer 1

Liora 1,810 Independent Advisor

Dear @Matthew Henrich,

I hope you’re having a good day.

To help narrow down the cause, could you please clarify a few things?

Are you using a Microsoft 365 Exchange Online mailbox, or is this an IMAP account (such as Gmail or another provider)?
When these emails disappear or reappear in New Outlook, do you see the same behavior in Outlook on the web?
Do you access the same mailbox from other devices or mail clients (mobile phone, Outlook Classic, Apple Mail, etc.)?
Do you have any Inbox Rules, Sweep rules, or Power Automate flows configured that could be moving messages automatically?

In the meantime, I would recommend a few quick checks:

Compare New Outlook with Outlook on the web

When an email reappears in the Inbox or disappears from the Flagged list, check the same message in Outlook on the web.

This will help determine whether the change is happening in the mailbox or only in the New Outlook client.

Review Inbox Rules and Sweep rules

Verify that there are no rules automatically moving messages between folders.

Screenshot 2026-09-14 at 18.14.32

Test with a single message

Move one email to a folder or flag one email that you can easily track.

Monitor whether that specific message changes location or loses its flag over the next few days.

Use Classic Outlook temporarily

Since you mentioned that this behavior did not occur in Classic Outlook, you may want to temporarily switch back to Classic Outlook if the issue is affecting your workflow.

Please understand that our initial response does not always resolve the issue immediately. However, with your help and more detailed information, we can work together to find a solution.

Warm regards,

If the answer is helpful, please select "Yes, accept answer". If you have any questions or new updates, please feel free to comment below.

Liora 1,810 Reputation points Independent Advisor

2026-09-15T15:38:02.7733333+00:00

Hi Matthew,

I hope you're having a great day.

I'm following up to see if you've made any progress with this issue or if there are any updates you'd like to share.

Wishing you all the best, and I look forward to hearing from you.

Kind regards.
Matthew Henrich 0 Reputation points

2026-09-15T17:24:17.05+00:00
I may try this, I like your idea of testing with a flagged email. It's usually over a span of weeks to months that messages disappear. I suspect it has something to do with synchronizing local files.

I know for certain I don't have rules.

May try this.

I will likely end up reverting to classic.
Matthew Henrich 0 Reputation points

2026-09-15T17:27:58.71+00:00

Another quick update. I opened up classic and all my old flagged emails are there from years ago that I had completely forgot about. None of these are in my flagged email list in new outlook. Is this some sort of intended function? Why would new outlook scrub old flagged emails from my list?
Liora 1,810 Reputation points Independent Advisor

2026-09-16T08:44:40.7066667+00:00

Hi Matthew,

Based on your description, I found a few things that may be relevant.

The fact that your older flagged messages still appear in Classic Outlook suggests the messages themselves have not been removed from the mailbox. Instead, the difference may be related to how New Outlook surfaces flagged items. Microsoft notes that flagged emails are integrated with Microsoft To Do, which is a different experience from the traditional Tasks/To-Do Bar used in Classic Outlook.

For reference: Using Microsoft To Do with flagged email from Outlook | Microsoft Support

I also found a similar report from another New Outlook user who observed that most flagged messages appeared to disappear, but could still be found using the Outlook search query: IsFlagged:yes

In that case, the flagged messages still existed but were not appearing in the expected Flagged view.

It may be worth trying IsFlagged:yes in New Outlook and comparing the results with Classic Outlook. If the missing messages appear in search results, that would suggest the items still exist in the mailbox and that the issue is related to how New Outlook is presenting flagged messages rather than the messages being deleted.

I would also still be interested in whether those same older flagged messages appear in Outlook on the web. If they appear in Classic Outlook and Outlook on the web but not in New Outlook, that would further point toward a New Outlook-specific behavior or limitation rather than a mailbox issue.

Kind regards.
Liora 1,810 Reputation points Independent Advisor

2026-09-18T10:28:08.5033333+00:00

Good day.

I wanted to check in and see whether you've had any new findings or updates regarding this issue. If you've had a chance to do any additional testing, please feel free to share the results, and I'll be happy to help review them.

Kind regards.
Matthew Henrich 0 Reputation points

2026-09-18T11:10:36.6666667+00:00

I'm just going to use classic full time. I need on my emails to be reliable as a source of "to do" actions when I don't have the time to address them right away. I'm not going to randomly search flagged emails every so often just because outlook decides to hide them. That also doesn't account for the 3 week old emails that get hidden randomly on me too.

I also didn't mention that I've had issues with important sent emails not showing up in my sent folder right after I sent them. I had to call someone to confirm they received my email.

I'm very disappointed with new outlook and will not be going back as long as classic is available.
Liora 1,810 Reputation points Independent Advisor

2026-09-21T15:04:07.24+00:00

Hi Matthew,

Thank you for the update and for sharing your experience.

Based on what you've described, the issue appears to extend beyond flagged emails alone, since you've also observed older messages reappearing in the Inbox and sent messages not consistently showing in Sent Items. The fact that these items remain visible in Classic Outlook suggests the mailbox data itself is still present.

Given how important email reliability is to your workflow, continuing with Classic Outlook sounds like a practical choice for now.

Thank you again for providing these additional details, as they may also help other users who encounter similar behavior. If you need any further assistance or have new findings to share in the future, please feel free to reply here.

Kind regards.

Answer 2

What is described matches a few Outlook behaviors and known sync issues rather than a single user setting.

The most relevant checks are:

Check whether the messages are actually hidden by view or Inbox layout
- In Outlook, verify the Inbox is not filtered.
- If Focused Inbox is enabled, check both Focused and Other.
- If preferred, turn Focused Inbox off in Settings > Mail > Layout > Focused Inbox so all mail stays in one list.
- If items are present in search but not visible in the folder, a view filter can also hide them. In classic Outlook, this is checked under View > View Settings > Filter.
Confirm whether this is a sync/display issue
- If the messages appear later in the Inbox even though they are older, that can indicate they were present in the mailbox but not visible in the Outlook client at the time.
- A documented Outlook issue exists where messages synchronized to the mailbox may not appear in the Cached mode Inbox because they become stuck in the incoming item processing pipeline.
- In that case, the supported Outlook for Windows resolution is:
  1. Exit Outlook.
  2. Start Outlook with:
```
        Outlook.exe /cleanips
```
  3. If that does not help, clear and resync the Inbox offline items:
    - Right-click Inbox > Properties
    - General tab > Clear Offline Items
    - Confirm removal from the .ost
    - Select OK
    - Select Inbox and press Shift+F9 to force resynchronization
- Risk note: Clear Offline Items removes the local cached copy from the .ost for that folder and then resynchronizes from the server. It does not describe deleting mailbox data from the server, but the folder will need time to resync.
Check whether older mail is being shown inconsistently because of sync scope
- Outlook can show only a subset of items kept offline in some scenarios, especially for shared mailboxes or public folders. If older items are missing, look for a message at the bottom of the message list such as Currently displaying all messages newer than...
If mail is visible in search but not in the Inbox list
- That strongly points to either:
  - Focused Inbox placing items under Other, or
  - a folder view/filter issue, or
  - a client sync/display problem rather than actual message loss.
If the account is Outlook.com with a connected account
- There was a known issue where deleted mail reverted back to the Inbox for Outlook.com accounts syncing from a connected account, but that issue is documented as fixed.

Based on the symptoms, the strongest matches are:

Focused Inbox or filtering hiding messages from the main list
a New Outlook/Outlook sync-display issue where items are delayed, disappear, or reappear in the Inbox