The archer with better aim beats the archer with more arrows.

I am a consumer. During the summer, I work with the marketing team at Net Atlantic, an email marketing provider. But nine months of the year I’m just an average student. I’m the person that reads those emails you send out and, if they’re interesting enough, I click through to your site. If you’re lucky, I just might buy something.

So today you get a little “outside perspective.” I may not analyze CTRs or market segmentation patterns, but I spend a few minutes every day looking through the dozens of emails I get from all sorts of companies and I know what makes them appealing.

First of all—and I can’t emphasize this enough—there is no universal set of rules that applies to every single email marketing campaign in the world. Do what works for you. As a toy collector, if I’m scrolling through my inbox and I find a message with a huge image of a shiny new figurine, I’ll be drawn to it. But that doesn’t mean every shoe store and furniture emporium should have pictures of action figures in all of their emails.

One of the few things you definitely should do, no matter what kind of company you are, is know who you’re targeting. Be familiar with your list and do everything you can to deliver relevant content. If I get an email offering exclusive deals on designer suede jackets, it wouldn’t grab my attention. If the recipient of the email were, say, my mother, the results would differ significantly.

But wait a minute. What’s the big deal? If somebody gets an email they don’t want, they’ll just delete it, and that’s that. As long as you reach enough people who are interested, there’s no harm done…right?

Well, the fact is, even if you do end up reaching your target audience, enough irrelevant messages could turn people off. For example, I bought some movie tickets online a while ago, and now I keep getting emails from Fandango about movies I don’t want to see. Eventually, I stopped opening their messages because they were never relevant to my interests. Now I simply disregard their emails.

But let’s say a new movie comes out that I’m actually interested in seeing, and I get an email offering me a free pack of Twizzlers if I buy a ticket. That’s an excellent chance for them to earn back a customer. It’s exactly what I want, and I’ll probably start buying from them again if my experience goes well. But if their email doesn’t catch my eye, we both miss out on a great opportunity.

However, keeping me engaged could avoid such a situation. If they kept track of my purchase history, they would know that I’ve gone to see The Avengers three times. So instead of filling up my inbox with pictures of Liam Neeson on a boat, they could send me stuff about that new Spider-Man movie. Then when it comes out, I’ll get my free Twizzlers, and Fandango will get a happy customer. So happy, in fact, that I’ll probably tweet about it. Now Fandango gets even more customers, all because they appealed to my interests, and kept me engaged.

You’re not going to see those results by just sending out the same email to thousands of people every day. Sure, it works fine, and people have been doing it successfully for years. But the difference between a good email marketing campaign and a great one is not the size of the list, but the efficiency in which the list and its data are used.