Mack-bot is run by steemcleaners. It's because you're on spaminator's blacklist. Mack-bot will downvote everything you post with a small percentage as a "warning shot", then spaminator will come and zero out your posts on day six if I'm not mistaken.

If you're planning to start posting again, we'll have to talk to @guiltyparties about getting you off the blacklist, because spaminator is a bitch. That account has 2.9 million Steem Power and will wipe out all of your rewards without even flinching.