I was in Montenegro at an AI conference when the reports started coming in. On vacation. Which is exactly when this stuff always happens 🤦♂️ Clients telling me replies had gone soft. Not off a cliff, nothing dramatic. Just quietly worse. So I sat in a hotel room with my laptop and Claude Code instead of doing any of the things you go to Montenegro to do, and started running tests. Here's the part that made me stop caring about the vacation. We found domains sitting on a blacklist before they had sent a single email. Not before their first cold email. Before they ever entered a warmup pool. Zero sends. Zero complaints. Already burnt. You cannot burn a domain that has never sent anything. So it wasn't the copy. It wasn't the warmup. It wasn't the volume. We tested all of it and none of it moved. Then we found the cause, and I did not enjoy it. It's a setup I've been telling you to use for years. In this community, in my paid programs, everywhere. Every serious infra provider in the space did the same thing, because it was the gold standard. It isn't anymore. It's now one of the easiest ways to get spotted as a cold emailer, and there's a blacklist quietly picking people off because of it. We ran a clean test that proved it in under an hour. Then we built two fixes and deployed them for all new orders before making this public. Both fixes are in the video, along with how to check if you're already on the list and what to do if you are: https://www.youtube.com/watch?v=CYoh_2j6VMg Watch it before your next send. If you've bought domains in the last few months, you're the one this happened to.