Great way to engage your users by sending automated emails, based on their behaviour.Add your suggestion Subscribe to this list
Easy to setup and friendly prices (if you don't have to many free users on your platform).
The Engage-package is great for startups who are running a Saas-company. Engage your users, or even upgrade your freemium users, by sending great emails.
Whenever you need to send e-mails through an API, Mandrill offers an extensible templating engine (if you are an advanced MailChimp user, you can use their HTML-ish syntax on here as well).
Data driven integration with your application. You can set triggers to send e-amils or even push notifications into your app.