Did you know that more than half of all iPad owners would rather use their iPad to read and send email than either their phone or their computer? That’s the finding of a recent survey of U.S. iPad owners by email software provider Perion. And you need to pay attention if you rely on email marketing in any significant way.

Conducted in the last half of 2012, the survey found 55% of respondents indicating their tablet was their preferred device for reading email (compared with 32% preferring their computer and 10% their phone) and 48% choosing the tablet to write email (compared with 41% preferring their computer and 9% their phone).

That may or may not surprise you. But what it definitely should do is make you believe that you need to be previewing your emails on iPads before you send them.

You already know how popular the iPad is. Tablet demand is huge in the United States, and Apple’s products remain far and away the most popular, despite increasing competition from both Android and Windows models. When Apple launched its (then) new iPad mini and 4th-gen iPad in November 2012, it sold more than 3 million of the devices in just three days. eMarketer estimates there will be 65.7 million iPad users in the U.S. in 2013, representing 60% of the total tablet audience.

But have you looked recently to see how your emails display on iPads? Have you ever looked? You’d better.

Even if you don’t have the resources to preview every email on an iPad before sending it, you need to at least test your templates to make sure they render well. Once you’re confident those are iPad-optimized, you might be able to get away with spot-checking intermittently in the future. Yes, it’s more work; but do you really want to risk losing this growing segment of your email audience?