DELETED_5350

[ChrisB]

Tools>Account Settings>mail.box.Name>Junk Settings> Move to Folder

 

[ChrisB]

I've got mine on IMAP stored on my server. Anything flagged as Junk either by thunderbird or spamassassin is moved to the deleted folder on the server.
The Junk rule is set to delete after 2 days, mainly so I can check there's nothing important moved there.