engineering
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Your Own Mail, No Open Ports
Self-hosting email is supposed to be dead. The ports are blocked, the reputation systems are rigged, and the people who tried it longest quit in public. Two founders ran their own mail anyway, on a server with no mail port open to the internet. The messages arrive over HTTPS. Here is the architecture, what it costs, and everything that broke.
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The Key That Expires
A plain SSH key works on every server that lists it, until someone remembers to remove it. A certificate signed by a security key in your pocket works for two hours, then stops. This is how we open short, logged windows into our servers with one touch, and the commands to do the same.