MailReplay

MailReplay is a web app + API that lets teams record, sanitize, and replay real email sends in a safe staging environment. Instead of relying on synthetic test data, it captures production email events (templates, headers, attachments metadata, provider responses, bounces, complaints) and replays them against a sandbox SMTP/API target to validate rendering, personalization, localization, and deliverability signals before releases. It includes deterministic “time travel” replays for incident debugging: pick a timeframe, replay the exact email stream, and compare outputs across versions. The product focuses on engineering workflows: CI checks that fail builds when templates break, unsubscribe links mismatch, or provider responses degrade. It’s not a deliverability magic wand; it’s a reliability tool that reduces regressions and speeds up postmortems. Privacy is handled via field-level redaction, hashing, and allowlisted capture rules so sensitive PII never leaves the customer’s environment.