Testing
HTML email templates can behave unpredictably when viewed across different clients. Outlook's Word engine may strip modern CSS, Gmail can rewrite <style> blocks, and Dark Mode settings might invert colours in ways that affect readability. Rendering outcomes vary between environments, and platforms frequently update. For these reasons, cross-client testing is an essential part of releasing emails across NSW Government systems.
Testing in continuous integration pipelines
Some NSW Government teams use continuous integration (CI) tools that include email testing as part of the development process. These CI tools may be connected to third-party services that generate rendering previews, check for spam triggers and manage stakeholder review flows. A typical setup might use GitHub Actions to trigger automated tests, including screenshot comparisons, with results fed back into the build process.
By integrating automated testing into the CI workflow, teams can identify rendering issues early—before emails reach production.
The action uses the open-source litmus-api wrapper and the standard pull_request trigger in GitHub Actions. This process ensures developers receive visual feedback before code reaches the main branch.
Overview of available platforms
A range of commercial platforms are used to test, review and validate email rendering. Below is a summary of selected services currently in use across the broader digital sector. This list is not exhaustive and does not indicate endorsement.
Offers previews across multiple clients and devices, pre-flight checklists, and collaboration tools.
May have fewer asset-management and personalisation tools than some alternatives.
Captures test emails from non-production environments and provides spam scores, header analysis and HTML validation. Supports API-based automation.
Does not provide cross-client previews; another service may be required for visual testing.
Provides screenshots for selected desktop, mobile and web clients. Integrates with end-to-end test frameworks through a REST API.
Client coverage may be more limited than larger platforms. Pricing is based on test volume.
Offers an email code editor, accessibility checking, and modular components. Supports integration with Git-based workflows.
Requires integration with third-party services for full rendering preview coverage.
Provides client previews, spam checks, review tools and CI-compatible API.
Some pricing models are based on credit usage or seat count.
Selecting a testing approach
Each platform and tool has different strengths and constraints. NSW Government teams may choose one or more options based on project needs, such as rendering coverage, automation capabilities, accessibility checks or review workflows.
Email testing is most effective when built into early stages of development. Ensuring visual consistency, readability and compliance with accessibility standards before publication helps reduce errors and supports a more inclusive user experience.