Selenium remains one of the most widely used tools for automation and end-to-end testing, especially in teams running large, cross-browser test suites in CI/CD. With Selenium 4.40, the project continues its incremental evolution: no dramatic breaking changes, but meaningful improvements that make real-world test automation more reliable and easier to debug.
For teams running Selenium email testing, OTP testing, or password reset email flows with Mailosaur, these updates help strengthen the browser side of end-to-end tests, particularly where UI actions and email verification intersect.
So let’s take a look at what’s changed in Selenium 4.40, how those changes affect email-driven end-to-end tests, and how to apply best practices when using Selenium with Mailosaur.
What’s changed in Selenium 4.40
Selenium 4.40 builds on the Selenium 4 foundation rather than redefining it. The focus remains on standards compliance, observability, and stability across browsers, grids, and CI environments.
BiDi support
Selenium’s bidirectional (BiDi) protocol support continues to mature in 4.40. BiDi allows Selenium WebDriver to both send commands to the browser and subscribe to browser events in real time.
This is particularly relevant when monitoring browser behavior during complex navigation, observing console output and runtime errors and improving reliability in Selenium WebDriver–based test frameworks.
While BiDi is not required for Selenium email testing, it improves insight into what happens in the browser after an email link or OTP is used.
Better logging
Selenium 4.40 includes ongoing improvements to logging consistency and structure across language bindings such as Java, Python, C#, and Javascript.
Improved logging will help teams diagnose test failures in CI/CD integration, correlate browser-side errors with test steps and debug failures that only occur in Selenium docker or Selenium grid environments. This is especially useful in email verification flows, where a test may fail after an email is successfully received but before the UI reaches its final state.
Updated WebDriver features
Selenium 4.40 continues to refine WebDriver’s alignment with W3C (World Wide Web Consortium) standards. This includes ongoing updates to browser options, session handling, and compatibility with modern browser releases.
For teams maintaining a shared Selenium framework, or using patterns like the page object model, these updates reduce inconsistencies across browsers and environments, particularly when running parallel testing or headless testing.
Infrastructure improvements
Behind the scenes, Selenium 4.40 includes updates that improve infrastructure and dependency. This includes better grid stability, and improved CI execution in tools like GitHub Actions and Jenkins, as well as compatibility with cloud-based test runners. These changes don’t alter how tests are written, but they do improve reliability for large testing suites running at scale.
How Selenium’s new enhancements improve end-to-end email testing
Email verification tests combine multiple systems: frontend UI, backend services, and email delivery, and while Selenium 4.40 doesn’t change how emails are sent or received, it does strengthen the browser automation layer that drives these workflows.
DevTools and BiDi support make browser automation more reliable With improved DevTools and BiDi support comes better visibility into what happens after an email-driven action, such as clicking a verification link or completing a two-factor authentication flow.
Ultimately, this makes it easier to understand failures caused by redirect issues, or network or authentication problems which are triggered by clicking links within emails.
For email verification tests, this reduces guesswork when diagnosing failures.
Benefits for end-to-end flows combining UI and email verification In real-world end-to-end testing with Selenium, email is rarely the final step, with common flows including:
- Account sign-up and email confirmation
- Password reset email workflows
- MFA testing and email OTP testing
- Testing email notifications triggered by user actions (transactional emails)
This new update’s stability improvements help ensure that once your email testing tool confirms an email has arrived and been validated, the browser can reliably continue the user journey. This is particularly important in CI environments where timing issues are more likely to surface.
Selenium and Mailosaur best practices
Selenium updates are most effective when paired with a strong email testing tool. Mailosaur is designed to work alongside Selenium by handling email and SMS validation via an API, rather than browser automation.
Mailosaur provides simple and intuitive quick-start guides for integration with Selenium, and specific guides for email and SMS testing, as well as language-specific guides too.
Handling async flows with modern Selenium
Email workflows are inherently asynchronous. Best practice is to let Mailosaur handle waiting, retries, and message validation and let Selenium focus on browser actions and assertions.
Selenium 4.40’s improvements to logging, session handling, and grid stability make this separation cleaner. Rather than relying on arbitrary sleeps or UI polling, teams can build more resilient email verification and test email workflows by combining explicit waits in Selenium with Mailosaur’s purpose-built APIs.
So, while Selenium 4.40 doesn’t radically change how email testing works, that’s a good thing! Instead, it reinforces the browser automation layer with better observability, stability, and standards alignment.