It's nice to have a reference like this, but as the comments on this thread display, everyone has their own preferred variant(s).

It's silly to think that there is a "one size fits all" email intro framework. Different contexts require different amounts of background information and introducer participation.

Really, the greater theme at play is the need for people to think more about how their actions (here, nearly effortless electronic ones) effect others. Sending email intros without understanding the benefits and detriments to both sides is impolite at best and downright rude at worst.

The Golden Rule applies, even to email.