As you can see, my fortress is filled with miasma, which is generated by lots of rotten dwarf corpses. I have a corpse stockpile outside and one idle dwarf who has Refuse Hauling labor enabled. I've waited for quite a while, but he is still under no job state. Why?
Best Answer
What! You are dumping dead dwarves on your garbage heap? You insensitive cad! Dwarves like to be buried, in coffins (carpenter/wood) or Sarcophagi (mason/stone). Once you make some and install them in a tomb room, your dwarves may bury the dead dwarves there. Even though this may not solve your miasma problem from rotting things other than dwarf bodies, this may solve your dwarf body problem, since miasma doesn't occur once the bodies are in a coffin. I believe that by default all your dwarves have the burial labor turned on, and the weird DF behavior regarding hauling garbage outside the fortress doesn't apply to the burial labor.
Update: apparently dwarves refuse to treat dwarf bodies or body-parts as garbage in the most recent versions, so your regular garbage hauling should work to stop miasma on things other than dead dwarf bodies, but you will need a tomb for dead dwarfs.