They just raised their pricing by 8x and they didn't give their users any notice. All the said was oh we're merging mailchimp and mandrill accounts in an email, not telling users that their also going to get fucked over because the price is now 8x higher.
I prepurchased several thousand dollars with mandrill in credits at the previous price, and they won't provide me with the service at the previous price even for my prepaid credits. wtf?
let's all move to amazon SES, most startups have free AWS credits, else it $0.10c per thousand, an eight of the price of mandrill,
here's how you multithread to send bulk campaigns on Amazon SES:
http://stackoverflow.com/questions/16834279/amazon-ses-php-sdk-2-how-to-achieve-high-send-rate