A lot of people don't use email as social media anymore, though, but rather mostly one-way communication with big entities like your bank, many of which aren't

A lot of people don't use email as social media anymore, though, but rather mostly one-way communication with big entities like your bank, many of which aren't expected to reply back. As this is a marketing company, they may also have the distinction that social media marketing generally involves having people socially convince you that something is good; but email is not a good forum for that.