The storage limit does not affect the managed custom folder if you copy messages into this folder by using Outlook Web Access (OWA)

On a computer that is running Microsoft Exchange Server 2007, you create a managed custom folder and then specify the maximum size for that managed custom folder. However, if you copy messages into the same managed custom folder by using Microsoft Office Outlook Web Access (OWA), the storage limit does not affect the folder.

The storage limit is not checked for the managed custom folder when you copy messages into that folder.

To resolve this problem, install Update Rollup 1 for Exchange 2007 Service Pack 2.
For more information about Update Rollup 1 for Exchange 2007 Service Pack 2, click the following article number to view the article in the Microsoft Knowledge Base:

For more information about how to create a managed folder, visit the following Microsoft Web site:
http://technet.microsoft.com/en-us/library/bb125163.aspx

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.