Some folders are not visible in Outlook on the web

Applies to: Exchange Server 2016 Enterprise EditionExchange Server 2016 Standard EditionExchange Server 2013 Enterprise More

PROBLEM


When you view a mailbox in Outlook on the web (formerly known as Outlook Web App [OWA]), some of your folders are not visible. When this issue occurs, it's typically the Sent Items folder that's not visible.

CAUSE


This issue occurs when the mailbox contains too many folders. The maximum number of folders in a single mailbox that Outlook on the web can display at one time is 10,000. 

To confirm that this is the issue that you're experiencing, determine the number of folders in the mailbox. To do this, follow these steps:
  1. Do one of the following, as appropriate for your situation:
  2. Run one of the following commands:
    • To display the results on the screen, run the following command:
      (Get-MailboxFolderStatistics <alias@contoso.com>).count 
    • To send the results to a .txt file, run the following command:
      (Get-MailboxFolderStatistics <alias@contoso.com>).count > c:\output.txt 

SOLUTION


To resolve this issue, reduce the total number of folders in the mailbox to fewer than 10,000.

MORE INFORMATION


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