outlook emails

Question

Outlook is not pulling in all emails.

When I open my email server, it has 10% more messages than Outlook.

They aren't all spam, rather legitimate messages.

Answer 1

Hi Martha Mahowald,

I understand how concerning it can be to find that the mailbox on the server contains more legitimate messages than Classic Outlook.

At this point, I recommend that you review and try the steps provided in the AI generated answer on your thread. That reply typically include the most relevant checks for this scenario. 

Since the difference is around 10%, I suggest first checking whether a synchronization filter has been applied to the affected folder:

• In Outlook, right-click the affected folder, such as Inbox, and select Properties.
• Open the Synchronization tab and compare Server folder contains with Offline folder contains.
• Select Filter and check whether any criteria are enabled. If no filter is needed, select Clear All.
• Return to Outlook, open the Send/Receive tab, and select Update Folder.

If this is a Microsoft 365 or Exchange account, please also check whether Outlook shows a message such as “There are more items in this folder on the server” at the bottom of the message list. This may indicate that Outlook is keeping only a limited period of email in its local cache.

To help narrow this down, could you confirm:

• Who is your email provider?
• Is the account configured as Microsoft 365/Exchange, IMAP, or POP?
• Are the missing messages mostly older emails, recent emails, or both?
• Does the mismatch affect only the Inbox or multiple folders?

Please do not post your email address or account credentials publicly. You can also refer to Microsoft’s guidance on Synchronization issues between Outlook and Outlook Web App and the available Classic Outlook troubleshooters.

I hope these checks help identify whether the messages are being filtered, partially cached, or failing to synchronize. Please share the results and the account type, and I’ll be glad to help you with the next appropriate step. Thank you so much for your understanding.   

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Answer 2

For Outlook for Windows, start with the checks that match missing-but-legitimate mail:

1. Verify Outlook can reach the internet.
   • Open a browser and confirm normal web access.
   • If the device is offline or unstable, Outlook may not download all messages.
2. Check whether Outlook is only showing a partial local cache.
   • In Outlook, go to File > Account Settings > Account Settings.
   • Select the Exchange account, then choose Change.
   • Review Mail to keep offline.
   • If it is set to a limited time range, Outlook may show fewer messages than the server.
   • Move it to a longer period or All, then restart Outlook when prompted.
3. If this is an IMAP account and folders appear but messages do not fully download, check for an IMAP server compatibility issue.
   • A known cause in Outlook 2013 and Outlook 2016 is that Outlook sends the UID SEARCH command.
   • If the IMAP server does not support UID SEARCH, Outlook may download the folder list but not all email messages.
   • In that case, the fix is on the mail server side: the IMAP server must be updated to support UID SEARCH.
4. Check common mailbox-side locations where legitimate mail may be placed.
   • Review Junk Email.
   • If Focused Inbox is enabled for the account, check the Other tab.

If the account is IMAP and the server mailbox consistently shows more mail than Outlook, the strongest documented cause here is IMAP server support for UID SEARCH. If the account is Exchange, the Mail to keep offline setting is the main Outlook for Windows setting to check first.

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• Outlook 2013 or Outlook 2016 IMAP account can't download messages because of UID SEARCH command
• Only a subset of items are synchronized in shared mailboxes or public folders in Outlook 2016
• I can't send or receive messages in Outlook
• Email is missing from your Outlook.com inbox