IdeaWell

Project ideas from Hacker News discussions.

Show HN: I wrote an email app that accepts only one sender per inbox

Original Article

Hacker News Discussion

📝 Discussion Summary (Click to expand)

1. Positive feedback on inbox cleanliness
Users appreciate the service for dramatically reducing unwanted mail.

“I have used this service since I found it on product hunt. I am loving it! My inbox is way cleaner now.” – cloudmanic
“Glad to know it's working for you!” – edpin2000

2. Desire for flexible bounce/block capabilities
Commenters highlight the value of being able to bounce or block individual senders or entire domains across all inboxes.

“This is amazing, my dream has always been that outlook, gmail, and the likes allowed for setting up bounce rules.” – hmokiguess
“Yes! And it can bounce/block any sender and entire domains too (across all your inboxes, if you choose).” – edpin2000

3. Broader call for whitelist‑only inbound messaging across communication channels
Several participants argue that email, text, and even snail mail should allow only known sources to reach the user.

“Email, snail mail, text messages etc. all need, IMO, options for ONLY allowing incoming messages from known sources. This seems like it is really aiming to do that for Email and I applaud the effort.” – jlm66

🚀 Project Ideas

Generating project ideas…

Unified Whitelist Firewall for Communication Channels

Summary

  • A centralized service that lets users create whitelist rules for email, SMS, and physical mail, automatically bouncing or blocking messages from unknown sources.
  • Core value proposition: one place to enforce “only known senders” across all communication channels, dramatically reducing spam and unwanted contact.

Details

Key Value
Target Audience Power email/SMS users, professionals, privacy‑conscious individuals
Core Feature Unified rule engine that whitelists senders/domains and bounces unknown incoming messages via provider APIs or webhooks
Tech Stack Node.js/Express backend, PostgreSQL, React frontend, Twilio/SendGrid/SMTP integrations, optional AWS Lambda for scaling
Difficulty Medium
Monetization Revenue-ready: subscription $5/mo per user, team plans

Notes

  • HN users expressed desire for “only allowing incoming messages from known sources” across email, snail mail, text messages (jlm66: “Email, snail mail, text messages etc. all need … options for ONLY allowing incoming messages from known sources.”)
  • Provides a practical utility that could be discussed on HN as a new take on inbound filtering, encouraging community feedback and open-source contributions.

Open‑Source Email Bounce Rule Engine

Summary

  • A self‑hostable application that plugs into any IMAP/SMTP mailbox to apply custom bounce/block rules based on sender address, domain, or headers.
  • Core value proposition: gives users full control over inbound email filtering without relying on proprietary provider features, with transparent logging and easy rule management.

Details

Key Value
Target Audience Developers, sysadmins, privacy‑focused users who run their own mail servers
Core Feature Rule‑based engine that can bounce (send 550 reject) or drop messages matching patterns, with web UI for rule creation
Tech Stack Go (or Python) for core, SQLite/Postgres, React/Vue UI, Dockerfile for deployment
Difficulty Medium
Monetization Hobby

Notes

  • Commenters praised the ability to “bounce/block any sender and entire domains” (edpin2000) and wished for such features in Outlook/Gmail (hmokiguess). An open‑source tool would let them implement exactly that.
  • Encourages discussion on HN about self‑hosted mail filtering, potential for extensions (e.g., integrating with fail2ban, spamassassin).

Inbox Guardian Browser Extension

Summary

  • A lightweight browser extension for Gmail and Outlook web that adds a “Bounce Unknown Sender” button, automatically moving or rejecting emails not on the user’s whitelist.
  • Core value proposition: brings powerful whitelist‑only filtering to everyday webmail users without needing to change email providers or run servers.

Details

Key Value
Target Audience Everyday Gmail/Outlook web users who want stricter inbound control
Core Feature UI to add senders/domains to whitelist; unknown incoming mail is flagged, moved to spam, or triggers an auto‑reply bounce via Gmail API/Outlook REST
Tech Stack Manifest V3 extension (HTML/JS/CSS), background service worker, OAuth2 for Gmail/Outlook API, optional Firebase Functions for bounce replies
Difficulty Low
Monetization Hobby

Notes

  • HN users liked the existing service that cleaned their inbox (cloudmanic) and wanted bounce rules across all inboxes (edpin2000). This extension delivers that directly in the UI they already use.
  • Simple to build and iterate; could spark discussion on HN about client‑side email management and inspire similar tools for other platforms.

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