No Bounce Handling Causing Sender Reputation Damage
Your application continues to send emails to addresses that have previously bounced (invalid addresses, full mailboxes, blocked domains). This damages your sender reputation score, causing email providers to throttle or block all your emails, including those to valid recipients.
Without bounce handling, your deliverability degrades over time. Emails that used to reach inboxes start landing in spam, then stop arriving at all. By the time you notice, your sending domain may be blacklisted and recovery takes weeks.
The issue compounds because every failed delivery attempt further damages your reputation, creating a downward spiral that affects all your users, not just the ones with invalid addresses.
Error Messages You Might See
Common Causes
- No webhook listener for bounces — The email service reports bounces via webhooks but the app has no endpoint to receive them
- Bounced addresses not flagged — Even if bounce notifications are received, the app doesn't mark addresses as invalid in the database
- No distinction between hard and soft bounces — Hard bounces (invalid address) should permanently stop sending, soft bounces (full mailbox) should retry then stop
- Suppression list not checked before sending — The app doesn't check a suppression list before attempting to send each email
- Catch-all sending to user-provided addresses — Newsletter or notification features send to any address without validation
How to Fix It
- Set up bounce webhook endpoint — Create an endpoint to receive bounce notifications from your email provider (SendGrid Event Webhook, Mailgun webhooks, SES notifications)
- Maintain a suppression list — Store bounced addresses in a database table and check it before every send
- Handle bounce types differently — Permanently suppress hard bounces immediately. Retry soft bounces 3 times over 72 hours, then suppress
- Validate email addresses at signup — Use email verification APIs or double opt-in to prevent invalid addresses from entering your system
- Monitor sender reputation — Use tools like Google Postmaster Tools and your email provider's reputation dashboard to track your domain health
Real developers can help you.
Prakash Prajapati
I’m a Senior Python Developer specializing in building secure, scalable, and highly available systems. I work primarily with Python, Django, FastAPI, Docker, PostgreSQL, and modern AI tooling such as PydanticAI, focusing on clean architecture, strong design principles, and reliable DevOps practices. I enjoy solving complex engineering problems and designing systems that are maintainable, resilient, and built to scale.
Anthony Akpan
Developer with 8 years of experience building softwares fro startups
Milan Surelia
Milan Surelia is a Mobile App Developer with 5+ years of experience crafting scalable, cross-platform apps at 7Span and Meticha. At 7Span, he engineers feature-rich Flutter apps with smooth performance and modern UI. As the Co-Founder of Meticha, he builds open-source tools and developer-focused products that solve real-world problems.
Expertise:
💡 Developing cross-platform apps using Flutter, Dart, and Jetpack Compose for Android, iOS, and Web.
🖋️ Sharing insights through technical writing, blogging, and open-source contributions.
🤝 Collaborating closely with designers, PMs, and developers to build seamless mobile experiences.
Notable Achievements:
🎯 Revamped the Vepaar app into Vepaar Store & CRM with a 2x performance boost and smoother UX.
🚀 Launched Compose101 — a Jetpack Compose starter kit to speed up Android development.
🌟 Open source contributions on Github & StackOverflow for Flutter & Dart
🎖️ Worked on improving app performance and user experience with smart solutions.
Milan is always happy to connect, work on new ideas, and explore the latest in technology.
Mehdi Ben Haddou
- Founder of Chessigma (1M+ users) & many small projects
- ex Founding Engineer @Uplane (YC F25)
- ex Software Engineer @Amazon and @Booking.com
PawelPloszaj
I'm fronted developer with 10+ years of experience with big projects. I have small backend background too
Krishna Sai Kuncha
Experienced Professional Full stack Developer with 8+ years of experience across react, python, js, ts, golang and react-native. Developed inhouse websearch tooling for AI before websearch was solved : )
Jaime Orts-Caroff
I'm a Senior Android developer, open to work in various fields
Sage Fulcher
Hey I'm Sage! Im a Boston area software engineer who grew up in South Florida. Ive worked at a ton of cool places like a telehealth kidney care startup that took part in a billion dollar merger (Cricket health/Interwell health), a boutique design agency where I got to work on a ton of exciting startups including a photography education app, a collegiate Esports league and more (Philosophie), a data analytics as a service startup in Cambridge (MA) as well as at Phillips and MIT Lincoln Lab where I designed and developed novel network security visualizations and analytics. I've been writing code and furiously devoted to using computers to make people’s lives easier for about 17 years. My degree is in making computers make pretty lights and sounds. Outside of work I love hip hop, the Celtics, professional wrestling, magic the gathering, photography, drumming, and guitars (both making and playing them)
Nam Tran
10 years as fullstack developer
prajwalfullstack
Hi Im a full stack developer, a vibe coded MVP to Market ready product, I'm here to help
You don't need to be technical. Just describe what's wrong and a verified developer will handle the rest.
Get HelpFrequently Asked Questions
What's the difference between a hard and soft bounce?
A hard bounce means the address is permanently invalid (user doesn't exist, domain doesn't exist). A soft bounce is temporary (mailbox full, server temporarily down). Stop sending to hard bounces immediately; retry soft bounces a few times before suppressing.
How do I recover a damaged sender reputation?
Stop sending to all bounced and unengaged addresses immediately. Clean your list to only active, confirmed recipients. Start sending low volumes and gradually increase. It typically takes 2-4 weeks for reputation to recover.