Back to the Basics: Are You Testing Your Emails?

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So, you’ve just sent your latest campaign. Naturally, you sent a copy to yourself, too. Maybe a Gmail account? Everything looks good and you’re ready to go about your day.

And then it begins…

Emails start rolling in from friends, colleagues, even your mom about how bad your email looks in their inbox. Your heart starts beating and your stomach drops to the floor. You scramble to see what went wrong before your boss notices, too.

The whole time, all you can think is:

What the $%!& happened?

Chances are, if you’re seeing a lot of rendering issues with your email campaign, you failed to properly test your campaign before sending it out. Sure, you may have sent yourself a test email which looked good, but if there’s one thing every email marketer should know, it’s this:

Not all email programs are created equal.

Just as importantly, not all of your subscribers are using the same email program as you. What looks good in your inbox has a high chance looking broken or mangled in someone else’s. Understanding why different email apps display emails in odd ways is the first step in ensuring that your next campaign looks beautiful in your subscribers’ inboxes.

The Rendering Engine

So, why exactly do email clients display the same email differently? It’s because they all use different rendering engines to display an email. The rendering engine is responsible for looking at the code in an email and figuring out how exactly to display the email in the application based on that code. Unfortunately, all rendering engines are different and they vary (sometimes wildly) in what code they actually support. Most rendering engines only support a limited subset of HTML and CSS—the building blocks of email—and, as such, many email marketers encounter rendering problems when they use unsupported code in their campaigns.

What’s more is that a few rendering engines have a number of known bugs. While they support the same code as other rendering engines, they don’t display that code in the same way. This leads to a lot of confusion amongst email marketers and designers who are unfamiliar with the various rendering engines in use today.

While we won’t go over each rendering engine and its quirks in this post, we have a number of resources that can help you understand the intricacies of the most popular ones:

On top of the problems associated with rendering engines, there are a host of other issues which could be affecting how your emails are displayed to subscribers.

Other Rendering Issues

Even assuming that your code is solid, there are other issues that could prevent your message from being relayed to your audience.

Image Problems

Email clients vary in how they handle images within an email campaign. For security reasons, a number of popular clients disable images by default, something we call image-blocking. Have you ever had Gmail ask whether or not you wanted to display images from a sender? Or have you opened up an email in Outlook only to be met with a bunch of empty boxes and broken image icons? That is image-blocking in action and it can be a big headache for email marketers.

We’ve written before about the importance of planning for an images-off scenario, but it’s worth reiterating:

Not everyone will see the images in your email campaign.

If the images in your campaign contain vital messaging, it’s important to understand what happens when those images are blocked. While you may see them during a test send to yourself, there is a good chance that a large portion of your audience won’t.

Even when images are displayed, a few things can still go wrong. Some email clients have trouble with images placed one next to the other and introduce gaps or white spaces around them. While there is a fix for that, it’s not likely something you would encounter without in-depth knowledge of email design or thorough testing.

Those Blue Links

One of the more common rendering issues happens on mobile devices. An email may look fine on your desktop, but when you actually open it up on your phone, some of the text is bright blue. Some mobile operating systems look for things that can be easily added to your contacts or calendar and highlight them as blue links in an effort to make a user’s life easier. While this is a nice feature in theory, it can lead to some disastrous results for email marketers.

Any one of these issues could be the culprit for that terrible email you sent out earlier. But, what can we actually do about it?

Enter: Email Preview Testing

We can test our campaigns—and not just by sending a draft to our own email account. It should be clear that’s not enough.

With Litmus, you can actually preview your campaigns in over 30 different email clients before you send it out to your list (or your boss). Your email is rendered using the actual email clients, allowing you to quickly identify problems with your design.

You can even disable images to make sure that your campaign looks good with images off. Plus, it’s easy to see any pesky blue links creeping in by previewing your emails on the most popular mobile email apps.


In short, you can send with confidence.

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