As direct marketers, we're all about testing. Without it, really, every campaign is a shot in the dark. If it doesn't work ... bummer. But, without testing, you won't know where it went wrong: the list, the creative, the offer. And, if it works ... great. But, why? You may never know that either.

There are many elements to test in an email campaign:

• HTML or Text
• Segmentation
• Body length
• Offers
• Headlines
• Calls-to-action
• Response options
• From
• Etc. etc. etc.

In fact, there are so many choices, analysis paralysis may set in. It's inarguably easier to do nothing.

BUT ...

If, like us, you respect the process and value of testing, there's an easy way to get started. And, to quote one nun-turned-governess-turned-bride-turned-international-singing-sensation, "Let's start at the very beginning."

Why not test the single element that can make-or-break your campaign before any other elements even get an opportunity to? The subject line. As direct marketers who started our careers before the advent of email, we think of subject lines as the digital equivalent of a classic direct mail package's outer envelope. A good subject line (like a good OE teaser) can inform, intrigue, amuse, enrage, mystify, or enlighten. But no matter what the words (and/or pictures) do, it has one mission above all else:

To get opened.

It's even easier to test subject lines than envelope teasers because the very first email metric most of us look at is the "open rate."

So here is a list of subject line tests you may want to employ on your next email campaign:

• Personalization
• Localization
• Segmentation
• Numbers
• Emojis
• Deadlines
• With or without offer
• Length
• Humor
• Urgency
• Cliffhanger
• Borrowed interest

Again, the list could go on and on, just like your testing should. But paraphrasing some classic direct marketing copy, if you test only one thing today, test the first thing your audience will see.

And that's enough on the subject.