Mandrill became part of the Mailchimp subscription. Only for paid accounts. Basically making costs for low-traffic projects way higher than they used to be if you didn't use Mailchimp with Mandrill. (Mailchimp subscriptions start at 10 $ a month)
After all the hate mail they recieved they opened up a free Mandrill plan if you are a paying Mailchimp customer. Who knows how long that will last though.
Basically I just recommend Mailgun or AWS SES now.