Cloud giant Rackspace has revealed that it’s spinning out Mailgun, its email automation platform for developers, as an independent company.

Founded in 2010, Y Combinator graduate Mailgun provides the backend technology that lets third-party developers send, receive, and track emails from within their own applications — it lets them know whether emails have been opened and then measure their impact. Rackspace acquired Mailgun in 2012 and has since offered Mailgun’s APIs as a value-added service alongside its core cloud offering.

The decision to spin Mailgun out comes less than six months after Rackspace itself was subject to a $4.3 billion deal to take the company private, after having traded as a public company since 2008.