Self-hosted email is nearly dead, and nobody has a fix

A thread on the steep decline of self-hosted email prompted a familiar but increasingly urgent discussion. The consensus: the Gmail and Outlook duopoly has effectively won, not through technical superiority but through spam filtering that preferentially trusts their own infrastructure. If you're not sending from Google or Microsoft, your mail has an uphill fight to reach inboxes.

The key insight from the thread: the only way to solve this without the duopoly is to solve spam without requiring centralized monitoring of users. Nobody has done that. The practical result is that independent email infrastructure is becoming infrastructure for the very patient or very principled, not a realistic choice for most businesses.

Several commenters noted they see no upside to a Google/Microsoft duopoly in email and called it clearly bad for the ecosystem, but frustration without a solution is just frustration.