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Email testing gem

Rails Mailer Sandbox

Preview customer emails and attachments locally inside Rails without a separate email-testing service.

Outcome

Captures persistent MIME messages with searchable previews, attachment downloads, and sandboxed HTML rendering.

My role

Open-Source Developer

How I helped

  • Built and published the open-source project.

Product

The workflow in context

Generated product visualization, not a live screenshot.

Generated visualization of Rails Mailer Sandbox email preview and delivery metadata.
Generated product visualization

The solution

Preview customer emails and attachments locally inside Rails without a separate email-testing service.

What changed

Captures persistent MIME messages with searchable previews, attachment downloads, and sandboxed HTML rendering.

Source

Explore repository.

AI system implementation

No AI runtime is involved. Action Mailer messages are captured as MIME files and rendered in a local inbox. Filesystem locking and atomic writes protect concurrent delivery; sandboxed HTML previews block scripts and remote resources. This is a deterministic development tool, not an AI email generator.

Could a similar approach help your business?

Tell me where work gets stuck. We can identify a practical first improvement and what success should look like.

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