How your email shows when it lands in the inbox is an important factor for users to decide whether they open it or not. So before you send your email, make sure you test it with our email inbox previewer and optimize your campaigns to increase your open rates:

Fill in the fields below and see how your email will show on mobile devices.

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Improve Your Email Open Rates with our Subject Line Tester

In email marketing, the subject line is crucial. It’s the first thing recipients see and often determines whether your email gets opened or ignored. Our Subject Line Tester can help you craft compelling subject lines and improve your campaign success rate.

What Does Our Tool Do?

Our Subject Line Tester allows you to preview how your subject line will appear on various mobile devices. The supported devices include iPhone 14, iPhone SE, iPad (10th Gen), Google Pixel 7, and Samsung S22 Ultra. By providing a view of how your subject line looks in the standard email client on each device, you can ensure that your subject lines are always clear, concise, and inviting.

Optimizing Your Subject Lines

An effective subject line is not just about the right wording – it also needs to fit well on the screen of the recipient’s device. We have a full guide on the subject line character limits of popular email clients, where we explain what we consider the ideal length. We believe the sweet spot is not going beyond 50 characters, especially considering some devices only display around 35 characters. So, it’s always wise to front-load the most important details in your subject line.

Our tool provides you with the chance to see how your subject lines appear on different screens, allowing you to optimize them for all kinds of devices. Find best practices for subject lines here.

Stay Up-to-date with the Latest Devices

Mobile technology evolves quickly, with new models and system updates constantly being released. Our Subject Line Tester keeps pace with these changes to ensure that you can optimize your email campaigns for the most popular devices currently in use.

Easy to Use

Our Subject Line Tester is straightforward to use. Simply input your subject line and click “Preview” to see how it will appear on various devices. This immediate feedback allows you to tweak and improve your subject lines for better email open rates and overall campaign success.

More Than Just a Tester

While our Subject Line Tester is a valuable tool, it’s just part of what we offer at We provide comprehensive reviews and comparisons of the best email marketing services to help you make the best choices for your email marketing needs. Among them are ActiveCampaign, MailerLite, GetResponse, Brevo and many more! You might also find our list of 10 free SMTP servers useful for transactional emails.

best esp comparison template


Questions or feedback about the Subject Line Previewer?
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01 Aug 2023 – Added character count