Certifying a mail server without a running web server

[cpu]

@dno

I should say that I have found a tool at https://mxtoolbox.com/ and it says my ip address (217.32.145.4) is blacklisted. I don’t know how this has happened since I only set the mail server up over the last couple of days.

Hi @dno,

That might impact your ability to send email but it wouldn't explain why both myself and the validation authority are unable to reach your server on port 443.