Please fill out the fields below so we can help you better. Note: you must provide your domain name to get help. Domain names for issued certificates are all made public in Certificate Transparency logs (e.g. https://crt.sh/?q=example.com), so withholding your domain name here does not increase secrecy, but only makes it harder for us to provide help.
My domain is: corkynan.com
It produced this output: Domain: mail.corkynan.com Type: unauthorized Detail: Invalid response from http://cn-mail.corkynan.com/.well... My web server is (include version): Turned off Apache 2 as certbot requested, so native to certbot The operating system my web server runs on is (include version): Debian 9 (Stretch) My hosting provider, if applicable, is: N/A I can login to a root shell on my machine (yes or no, or I don't know): Yes I have full access to all systems on the network. I'm using a control panel to manage my site (no, or provide the name and version of the control panel): No The version of my client is (e.g. output of `certbot --version` or `certbot-auto --version` if you're using Certbot): 0.10.2