Mark Junk Read

Yettwasezmel 5 ɣef 5 n yetran

sɛur David di Sept. 29, 2015 · aseɣwen yezgan

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!