The awkward silence of removing an anonymous feature nobody can email about

We recently put a simple email wall in front of our main tool to track returning users and stop abuse. On paper it makes total sense for product metrics, but communicating a downgrade to casual visitors is surprisingly brutal. Every draft announcement we wrote either sounded like PR spin or an apology for securing our own infrastructure.

For founders who transitioned from anonymous access to a mandatory free sign-up how did you frame the update to your audience?