Mark Junk Read

Z 5 z 5 gwězdkow pógódnośony

wót David dnja Sept. 29, 2015 · trajny wótkaz

Initially I had the same problem as fgilbert, my folder was named "Unerwünscht". The solution Alex Cabal suggested was to go to
Account Settings -> [Account] -> Junk Settings -> Destination and Retention
and set Thunderbird to move new junk messages to the folder in question. Now it works exactly as advertised. Thanks again!