This is not supported
This article applies to
Folder 'NAME' is not found in the mailbox 'NAME'
Acronis Recovery for Microsoft Exchange does not support Microsoft Exchange Server 5.5 in its format. See Microsoft Exchange Servers Acronis Recovery for Microsoft Exchange Supports.
Mailboxes of this type are not supported.
This situation is true for any type of mailboxes that were migrated from Microsoft Exchange Server 5.5 to any other version of Microsoft Exchange.
For example, if the mailboxes were migrated from Microsoft Exchange Server 5.5 to Exchange Server 2000 to Exchange Server 2003 to Exchange Server 2007, those mailboxes will still not be supported as they are stored in the original format.