It has come to my attention that some people dispute my way of replying to email threads. I elide all but the minimum necessary to supply the context.
Be brief without being overly terse. When replying to a message, include enough original material to be understood but no more. It is extremely bad form to simply reply to a message by including all the previous message: edit out all the irrelevant material.
That's from RFC 1855, people. You think you're better than an RFC‽ Come on!