There has been a debate going on for the past couple of years. Some say that email is dead and that the younger generation doesn't connect via email anymore. Others say that email is a commodity you can own and control, while social media is "rented" property, continually the victim of the fickle social media provider. I think it's a faulty dilemma to pose having to choose. Both have strengths and weaknesses. Both have a valuable presence and role in your communication strategy.
Your organization should be intentional with both email communication and active & present on several social media platforms. This infographic below compares the two, with both their strengths and weaknesses, in a side by side comparison.