"Ever get sent an e-mail with a blank or unintelligible subject line?
Maybe you get CCed on a long ping pong e-mail that only reveals it's
relevance in the very last reply.

Well, sometimes you need to file these away suckers for reference and
this is where the trouble begins. What was top of your mind a week ago
may now be completely opaque. So, when you browse through your mail
folders, looking for that vital bit of information, it seems next to
impossible to recall what all those e-mail exchanges were about? Where
is it?

Well there is an easy solution - change the subject line. Think of it
as personal tagging. It is very easy to do.

First, double click the e-mail (or hit enter) to open it in a separate
window. Then put your cursor on the subject line and start typing.
That's it. You can add your own reference - date, project number,
whatever - or change the subject line completely. Whatever is going to
be meaningful to you. Use as many words you like.

When you're done, Ctrl+S to save. "