I imagine there was some kind of crisis happening behind-the-scenes... That's the only explanation I see for the overnight policy change and lagging updates on the site. Either that or total incompetence.
Interestingly, their (former) competitors are taking full advantage of the outrage by running ads on Twitter and LinkedIn aimed at Mandrill customers who've been screwed.
I wonder if they found certain types of Mandrill users were destroying their deliverability metrics and were starting to cause issues with major email providers and their spam factors. These ESPs can't exist with poor desirability, so they have to put protecting that ahead of a lot of other things that might get them more customers.
Considering how good Mandrill's delivery was, I'd be surprised if this were the case. Even still, there are better solutions - cut the free tier off, for example!
This is my theory too. There must be something very broken in mailchimp's management. I can't believe that something this knuckle headed would come out of our well functioning management team.
Interestingly, their (former) competitors are taking full advantage of the outrage by running ads on Twitter and LinkedIn aimed at Mandrill customers who've been screwed.