Golang and Let's Encrypt: a free software story

https://dotat.at/@/2025-06-28-boulder.html Here's a story from nearly 10 years ago. the bug I think it was my friend Richard Kettlewell who told me about a bug he encountered with Let's Encrypt in its early days in autumn 2015: it was failing to validate mail domains correctly . the context At the time I had previously been responsible for Cambridge University's email anti-spam system for about 10…