Kiera Butler explains:
[E]mailsespecially those with attachmentsstill use energy and create greenhouse gas emissions, even if you don't print them. ... Part of the reason we have so much data has to do with redundancy: Let's say you take a picture and send it to 20 people. Each of those people then have to download it, which requires equipmentpersonal computers, servers, and storage centers. ... All of a sudden there are 7,000 copies, and because of that there are 7,000 devices that are being run to support that data.