Your email marketing will flunk if you ignore this message.

Your enemy in business-to-business email marketing is the preview pane.

Most individuals at work use the preview pane in their email program. The preview pane, of course, is that window that shows the contents of an email message before you open it. It usually appears beneath the email inbox. But it can also appear to the right of the inbox (in Microsoft Outlook, for example).

The problem you face is that preview panes show only the top part of your email message. So what you put at the top of your email is crucial in winning the attention (and the business) of your reader.

The secret to making the most of this priceless real estate is to remember that some preview panes show only the first two inches of an email. Two inches is the height of a standard business card. So, if you want to grab your reader’s attention and compel them to read on, write your opening so it fits onto a business card.

That means don’t put a honking great graphic (your logo, for example) across the top of your HTML email messages. That means don’t put links to other places here as well.

If you want to capitalize on the fact that most business people use the preview pane, and that a whopping 40 percent of most HTML emails are impossible to understand with graphics blocked (according to a 2006 study by Forrester Research), put your most important message in the top left corner of your email marketing messages.

Imagine that your business card is there. That’s a space two inches high by three and a half inches wide. This is your window of opportunity, if I may mix my metaphors for a moment. And it’s a tiny window. Make the most of it. On your business card, you don’t have space enough for extraneous information. And neither do you have enough space in your email promotions. If you lose your reader at the top left corner, you lose your reader.