A/B testing for email campaigns to maximize conversions in 2025

A/B testing for email campaigns encompasses one of the earliest forms of A/B testing; marketers have been optimizing subject lines, body copy, and send times for years. In 2025, however, experimentation is increasingly becoming a company-wide discipline, which means it is time to rethink how email fits into larger growth strategies.

Here’s how.

• What is A/B testing for email campaigns?
• Why experimentation data matters more than subject line tests
• How to run experiments that impact your email strategy
• Using Kameleoon to improve your marketing campaigns

What is A/B testing for email campaigns?

Traditionally, A/B testing for email campaigns involves testing the subject lines, CTAs, and other content to target top-of-funnel metrics like open and click-through rates. 

This approach makes sense, but exists in a silo. It enables the team sending the email to improve their own metrics, but there is no reason to stop there! 

That's because this approach doesn’t tell you what someone did after they clicked, has no way of integrating with a product strategy, and doesn’t influence outcomes beyond the inbox.

Kameleoon takes a different approach: rather than testing the emails themselves, we test the experience that leads to and follows from the email.

Why experimentation data matters more than subject line tests

An experimentation-led growth approach uses data to fuel email personalization. It works in three steps:

1. A visitor is bucketed into a variant for a pricing page experiment.
2. That exposure is recorded and sent to a third-party platform, like HubSpot or Klaviyo.
3. The visitor receives a follow-up email based on which version of the page they saw.

With this approach, the email becomes a triggered action as part of a broader experimentation program. It reflects what the user experienced, and gives the tester more data—and richer insights that help them understand their audience.

How to run experiments that impact your email strategy

To run experiments that impact your email campaigns, consider:

• Which on-site experiences should inform our post-click emails?
• What behaviors should trigger follow-up messages?
• For example, add-to-cart, variant exposure, or feature flag status
• What impact should each user segment have on the content or timing of the message?

Kameleoon allows you to:

• Create user segments based on experiment exposure or behavioral data
• Sync those segments to your email service or customer data platform (HubSpot, Klaviyo, Segment, etc.)
• Trigger tailored emails based on test performance

Here are a few real-world examples of this process in e-commerce and SaaS:

• E-commerce: A user is shopping for sneakers. They load up a retailer’s website and are exposed to a site variant that shows them a popup for free shipping on the product page for the brand they want. They see the popup, but don’t end up buying anything. Knowing that they saw the variant with the popup, the retailer sends them an email, reminding them about their free shipping offer to entice them to return to that specific brand page.
• SaaS: A lead visits your pricing page while you’re running a server-side test that includes two pricing tiers. Because of their segment, they see the enterprise version, so they enter an enterprise-specific nurturing sequence that triggers an email send with enterprise use cases.

Using Kameleoon to improve your marketing campaigns

Kameleoon’s unified platform is designed for marketers, product teams, and developers who want to collaborate in their experimentation. For marketers and product teams who want to explore A/B testing for email campaigns, Kameleoon allows marketers to go beyond isolated tests, thanks to: 

• Real-time integrations
• Client-side and server-side testing
• Segmentation control

A/B testing for email campaigns is evolving, and leading marketers are integrating their emails into full-funnel experimentation strategies. Kameleoon enables you to do exactly that—to test more than “just” your website, to test the full user experience. With Kameleoon, you can:

• Create user segments based on your mailing list
• Send marketing emails to your leads that trigger personalized experiments based on those segments Collect actionable insights and use them to improve each step of the marketing funnel
• Build a culture of experimentation that offers reliable insights across landing pages, product pages, and email to improve your campaigns.

Your competitors are experimenting every day. Don’t get left behind; equip your team with a best-in-class, unified platform that empowers experimentation across marketing, product, and beyond.