InboxFlood

About the startup

What is InboxFlood? InboxFlood exists because testing email deliverability on a brand-new inbox doesn't work. An empty inbox has no history — its filter has nothing real to learn from, so sending a test campaign into it and checking where it lands tells you almost nothing. How it works InboxFlood feeds an inbox hundreds of real, independently-run newsletters every day. That builds genuine mail volume — but volume alone isn't the training signal. The next step is engagement: opening, reading, and interacting with that mail the way a real person would. That engagement is what actually trains the filter. Once the filter has learned from real volume and real engagement, you finally have an inbox worth testing against — send your own campaign in and see, with real confidence, where it lands. Who it's for Cold email senders & agencies testing deliverability before scaling a real campaign Marketers who want to see what their entire niche is sending in newsletters, not just track one rival Developers & QA teams who need realistic inbox data to test how their systems handle real-world mail What makes it different Most tools in this space warm up inboxes by simulating engagement across a closed network of mailboxes sending each other fake conversations. InboxFlood doesn't simulate anything — every newsletter is real and independently run, and the engagement comes from an actual person, not a script. That's also why the same data works for competitive research and QA testing: in all three cases, what matters is that the mail is genuinely real.