Is email like cheese or is it like air?
Cheese is a finite resource – no matter how much you may like cheese you can only eat so much, your larder can only hold so much and all the cows + sheep + goats of the world can only produce so much. We could indeed run out of cheese!!!!
Air is an infinite resource – we do not even think about it save in very rare circumstances. It just exists and we can use as much of it as we like, indeed we do not even consider that we are using a resource – it is so invisible and ubiquitous.
Users of email think of it as being like air, providers of email services think of it like cheese.
Lost ConsCIOusness 
My experiences of university email accounts at various times during the last 11 years has been that university IT services regard email as chocolate pots: so rich they are best served in very small quantities.
My experience of the civil service is that emails are regarded like hydrogen. The most abundant element in the universe.
Perhaps I should call bullshit on the periodic table by suggesting that emailium is in fact the most abundant.
After all, it is not possible to CC hydrogen.
If breathing in and out were like receiving and sending email, many of us would have suffocated a long time ago.