Konica Minolta new C1070 series have envelope fuser for option.
But I see someone who do great printing on envelops on KM C8000, but they have extra fuser, and they manualy switch when they do small sufrace stuff, like envelope. That is not easy to do, your operater must have some knowledge how to put another fuser... and because of that is better to have PRESS C1070 with envelope fuser inline.