If this already is a feature I have not yet discovered it.
My suggestion is that, as part of the drone setup system, you add the provision to add items to the block list remotely. This would involve creating a third folder on all your devices called (maybe) “Block” or “SSBlock”. Anyway, when the main SpamSieve program on the drone server checked the TrainSpam and TrainGood folders it also would check the block folder and move anything in it to the block list. This would clear up overnight 90 per cent of the crap that goes daily into my Junk folder.
Well, what I’m really trying to do is designate certain (i.e. “most”) spams that have ended up in the Junk folder to go directly to Trash the next time I get a repeat of that email or something from the same sender. That’s what I thought the block list did, but I infer from what you said that block list items just go to Junk, not to Trash.
I’m saying that it already does what you’re asking for. A message that matches the blocklist will get a spam score of 99, and if you enable the Move it to the Trash if the spam score is at least option it will move such messages to Trash instead of Junk.