http://www.perlmonks.org?node_id=995020


in reply to Email subject lines should be written:

The correct answer is a combination of the first two: Before writing the body, it's a summary, so you should have an idea what you're going to say before you start typing. Think of it as a requirements document for the rest of the email.

A good subject line also gives the reader a reason to read it. Don't assume that your email is going to get read just because you send it.

xoxo,
Andy