When we think about testing websites and apps, most of us focus on the core UI — buttons, forms, modals, API responses. But what about the part of the user journey that happens outside your product?

I’m talking about emails — and not just marketing blasts, but the critical transactional messages users rely on: password resets, verification codes, welcome emails, and more. As a digital marketing manager, I’ve seen first-hand how overlooked this layer of communication can be — and how important it is to get it right.

Here’s why email testing should be a non-negotiable part of your QA strategy — and how devs and marketers can collaborate to make it happen.

Why post-signup emails matter more than you think

Imagine this scenario:

  1. A user signs up.

  2. The UI shows “Check your inbox to confirm your email.”

  3. The user never receives anything.

  4. They try again. Still nothing.

  5. They give up.

This isn’t a bug in your codebase. The frontend looks fine. But from a user’s point of view, your app is broken.

Transactional emails are part of the user experience.

When they fail — or show incorrect information, formatting issues, or broken links — users lose trust fast. Worse still, these emails often get the least attention in testing.

Common pitfalls in email-based user flows

Here are some all-too-common email issues that sneak into production:

🧪 No testing in staging: Email delivery might only be wired up in production, meaning devs can’t test flows properly pre-launch.

🪝 Webhooks misfiring: Trigger logic that should send an email isn’t firing correctly, especially after auth or third-party API updates.

🔗 Broken or expired links: Magic links, password resets, or confirmation links that 404 or don’t redirect properly.

🔤 Incorrect dynamic content: Emails showing the wrong user name, product name, or even language due to poor template logic.

🧠 No clarity in the message: The copy doesn’t explain what the user should do next — e.g., “click to verify” without explaining why.

These things aren’t just annoying — they directly affect conversion, retention, and customer support volume.

Tools that make email testing easier

If your team is skipping email testing because “it’s hard,” the good news is: it doesn’t have to be.

Here are a few tools that help developers and QA teams automate and validate email interactions:

Mailosaur – Great for automated testing. Works with frameworks like Playwright, Selenium, and Cypress. You can check that an email was received, inspect its contents, and even click links or extract OTP codes.

What to include in your email test suite

When testing post-signup communication, here’s a solid checklist to get you started:

✅ Email is triggered and received
✅ Subject line and sender are correct
✅ Personalization (name, product info) renders properly
✅ CTA or link goes to the right destination
✅ Content is clear and mobile-friendly
✅ Edge cases (missing data, invalid tokens) handled gracefully
✅ Multi-language versions work (if applicable)

Also test negative paths — e.g., what happens if a user tries to use a link twice, or if the token expires?

Final thoughts: Collaboration is key

Too often, email testing is treated like someone else’s job — devs handle the logic, marketing writes the copy, and nobody tests the full experience.

But if the goal is user success, both sides need to collaborate. Set up a shared test plan for email flows. Get copy into staging early. Use tools that let you QA emails like any other part of your product.

Because if users can’t get past the inbox, they’ll never reach the rest of your carefully built app.