The first thing I noticed was wrong was that my Iphone was giving me a pop up telling me it could verify the identity of mail.keldo.uk. My first though was that the ssl cert had expired but as far as I knew Mailcow should automaticly refresh the cert. Luckily it was easy to debug as mailcow has a nice selection of logs and I just open the acme logs and Imedialty saw the issue “mail.keldo.uk – Found AAAA record for mail.keldo.uk: 2a00:23c7:82c2:6401:be24:11ff:fe6d:10fa – skipping A record check” was apearing every hour. I setup ipv6 records when I set up mailcow however since I have a dynamic IP and haven’t set up a ddns for ipv6 it was seeing ipv6 skiping ipv4 and then seeing the ipv6 didn’t match. The simple solution was I just removed the ipv6 record and then the next hour it was fixed.
