Email Test Inbox for Developers
Point a staging app's SMTP settings at a shared test inbox, and preview every caught email's HTML, text, headers and links without any of them reaching real users.
Economics
- Pricing example
- $8/month per team (free: 100 emails a month)
- Daily math
- 75 teams x $8/month = $600/month, or $20/day.
- Target if you hit the daily math
- Target: $600 / month at about 75 subscribers
Audience and urgency
Audience: Developers and small teams testing transactional emails (sign-up, password reset, receipts) from staging environments.
Urgency: Sending test emails from staging risks reaching real customers, and checking templates across environments is clumsy. Local catchers don't help a whole team share one view.
MVP scope
- ✓ SMTP endpoint with per-inbox credentials that accepts and stores mail, never relays
- ✓ Web inbox: HTML, text, raw source and headers views
- ✓ Link list with status checks and a basic HTML/CSS warning list
- ✓ Retention limit (e.g. 7 days) and size caps
- ✓ Team invites; Stripe subscription
Omitted features
- - Do NOT relay or forward caught emails to real addresses
- - Do NOT accept mail without per-inbox credentials
- - Do NOT build a marketing email builder
Suggested stack
- Frontend
- Next.js + Tailwind CSS
- Backend or API
- Node SMTP server (smtp-server + mailparser) on a small VPS or Fly.io; Postgres + object storage
- Payments
- Stripe Billing
- Hosting
- Fly.io or a small VPS for SMTP; Vercel for the web app
Repository metadata
- Blueprint ID
email-test-inbox- Category ID
dev_tools- Monetization ID
micro_subscription
Day-one distribution
Channels
- Reddit r/webdev and r/laravel (follow rules)
- dev.to tutorial: testing password-reset emails in staging
- Hacker News Show HN
Reddit strategy
Share the free tier and the setup snippet for common frameworks.
Cold outreach or directory hook
List on developer tool directories and write framework setup guides (Laravel, Rails, Django, Node).
Search keywords
email testing tool for developers, fake smtp server for staging, test transactional emails
One-shot master prompt
Build an "Email Test Inbox" service: Node SMTP catcher plus a Next.js web inbox. Core requirements: 1. SMTP server (smtp-server library) on port 2525/587 with STARTTLS; AUTH required with per-inbox username/password; accept, parse (mailparser) and store messages; never relay. 2. Storage: metadata in Postgres, raw .eml and attachments in object storage; per-inbox size caps, max 10 MB per message, 7-day retention job. 3. Web inbox (magic-link auth, team invites): list with search; message views for HTML (sandboxed iframe), plain text, headers and raw source; attachment downloads. 4. Checks: list all links with HTTP status (HEAD requests, rate-limited), missing plain-text part, missing alt text, images over a size threshold. 5. Setup snippets for Laravel, Rails, Django and Nodemailer; free 100 emails a month; Stripe Billing ($8/month per team).
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Published 2026-10-08.
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