I have a deep affection for email and regard it as one of the most crucial components of modern communication, and to some extent, society at large.
But email is badly treated. Yes, it has flaws, but it accomplished something unique: an universal way to contact someone, for free, from anywhere on the planet.
In this post, I will rant about email, about what I love and what I hate. Some of it will be constructive, while most of it will be a graybeard grumbling about how society ruined something great.
I will use the term email to speak of everything, from protocols to the user perspective. It is an over simplification, but I reassure you and I'll brag about it just now: I know "a lot" about emails.
Also, when I say you I mean developers, sysadmin, webmasters but never users. Users are sacred, users are never wrong, users are like babies in cribs and should be looked after. This is important and should drive our industry.