We recently had an Issue with some of our clients where the Sent Items folder was showing properly but our Barracuda Archive could not archive because the Sent Items folder was actually named Sent Items.dup1
I ran the GWCheck Misc option FOLDERRESET
This resolved that issue, but now there is a NoSelect flag set on the Sent Items folder.
This NoSelect Flag is keeping the Barracuda from setting the retention flag.
I am being told by Barracuda to create a temp folder and move all the Sent Items folder contents to it, then delete the Sent Items folder, then rename the Temp folder to Sent Items.
Since the Sent Items Folder is a System older it cannot be renamed ;(

A snip from an IMAP log was this:
'error' => '8 NO STATUS Mailbox not selectable: Sent Items',
'user' => 'TESTUSER',
'folder' => 'Sent Items'