Symptoms
When you view Quota Thermometer to find the mailbox size and quota values in Microsoft Outlook and Microsoft Outlook Web App in Microsoft Exchange Server 2013, the results are displayed incorrectly, and a warning that says the quota has reached the limit is sent to your mailbox. Note You can run the Get-MailboxStatistics <mailbox> | fl and Get-MailboxFolderStatistics <mailbox> | fl cmdlets to find your mailbox size information.
Cause
This issue occurs because Exchange Server 2013 counts the size of the Recoverable Items folder into the overall quota.
Resolution
To fix this issue, install Cumulative Update 10 for Exchange Server 2013.
Status
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
