Drupal is an open source CMS that's geared toward power users who want lots of customization. High-profile sites like whitehouse.gov and data.co.uk build with Drupal, so it's no surprise that this is one of the more popular options available. MailChimp’s Drupal plugins let you unify your email marketing with your website. Choose from the modules below to sync existing Drupal users with a MailChimp list, create campaigns, and even use Mandrill to send out new user emails, password reminders, or general application notifications.