E-mail messages decay more and more towards short messages — without full sentences, without punctuation, and with a lot of ambiguous abbreviations, et cetera which leads to misunderstanding and the necessity to ask for details or how the message should be interpreted.
Take the time and write all E-mail messages like real letters: write what you want to express; keep an eye on style, language and grammar; do not forget punctuation or salutation; avoid ambiguous abbreviations; and proof-read the message at least once before sending or publishing.
email.is-not-s.ms is a personal policy that all E-mail messages regardless of reader or subject will be as long and detailed as necessary and not castrated by arbitrary and artifical limits which just needlessly cripple this medium. It's that simple.
See also: usenet.is-not-s.ms, jabber.is-not-s.ms, icq.is-not-s.ms, changelog.is-not-s.ms, etherpad.is-not-s.ms, irc.is-not-s.ms, and blogging.is-not-s.ms.