Before your email can be read, it must be open. The key to getting your email opened is the subject line.

Think of the subject line of your e-mail as being the equivalent of a headline in a sales letter. It's that important. In fact, if you don't write a good subject line, I can almost guarantee your e-mail will not be opened, not be read, and, in fact, end up in the trash.

So what makes up a good e-mail subject line? There are three essential components every subject line must contain. They are:

Without these three elements, your subject line will not draw your reader into your e-mail, and your e-mail won't be read.

Another way to think of this is to remember what your reader is always thinking: “what's in this for me?”

If you don't have a good answer to that question, you and your email are toast.