Article ID: 2535130 - View products that this article applies to.
Consider the following scenario:
Note The Versions folder item counts in the mailbox is very high (several million) when you run the following command to query the count:
Get-MailboxFolderStatistics -Identity <Your test mailbox> -Folderscope RecoverableItems | ft name, ItemsInFolder -autosize
This issue occurs because the IMAP4 service triggers an unnecessary copy on write (COW) action when it accesses the contacts item. Then, a recoverable item is created in the dumpster versions folder. Therefore, performance decreases when too many unnecessary recoverable items are in the dumpster versions folder.
To resolve this issue, install the following update rollup:
(https://support.microsoft.com/kb/2579150/ )Description of Update Rollup 4 for Exchange Server 2010 Service Pack 1
To work around this issue, use one or more of the following methods:
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
For more information about a similar issue, click the following article number to view the article in the Microsoft Knowledge Base:
(https://support.microsoft.com/kb/2463798/ )Performance in Outlook or in OWA decreases when you use IMAP4 to access the calendar folder in an Exchange Server 2010 SP1 environment
Article ID: 2535130 - Last Review: July 28, 2011 - Revision: 3.0