When compared to communication alternatives, email turns out to be on the low side on bandwidth, but in some contexts in makes up for the low bandwidth with its considerable velocity. This makes it especially useful for short, focussed communication and less so for lengthy diatribes. The use of email has definite social implications, although there isn't always agreement on what they are. This phenomenon added a new term, flaming, to our working vocabulary. Email can remove social distance as well as geographical distance as it suppresses status cues.
Email can support and sustain communities of interest.
Email can be a weapon in organizational politics. To be sure, there is a healthy body of literature which speaks to a variety of other social effects of email - in some cases, inconclusively. All of these are important areas of study, and equally beyond present purposes. Because of these benefits, the popularity of email soared. But this growth is not without discomfort.