Mailgun

Mailgun is a developer-focused email delivery platform that empowers companies to send, receive, and track transactional and marketing emails through an API. Founded in 2010, Mailgun became a Y-Combinator success story later acquired by Rackspace. In February 2017, Mailgun spun back out as a standalone business focused on building best-in-class email deliverability solutions. Mailgun enables developers to tightly integrate email into their apps, i.e. give real email mailboxes to their users, their web pages or any objects in their apps. Customers like Slack, Lyft, Github, and Reddit rely on Mailgun to deliver email to their customers.