When attempting a message level restore of a mailbox on an Exchange server from a Barracuda backup appliance, the restore may fail after short time due to size limitations.
Here are two possible fixes:
Above that tag add: <requestLimits maxAllowedContentLength="104200000" /> (size is in bytes)
Restart IIS using the iisreset command in Start/Run.
Please note that in most cases the maxAllowedContentLength value is not going to pre-exist, you will have to create it yourself.
Exchange Server 2007 has a default maximum accepted request length of 13MB. You may increase the maximum accepted request length by performing the following:
1. Open Windows Explorer
2. Navigate to C:\Program Files\Microsoft\Exchange Server\ClientAccess\exchweb\ews
3. Open the file Web.Config in a text editor such as Notepad
4. Find the XML tag starting with maxRequestLength=
5. Change the existing value to maxRequestLength="102400"
6. Save the file
7. Restart IIS using the iisreset command in Start/Run.