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:
I have no issues but I am asking for help, I have postfix server and Rukovoditel ERP and I need to setup the email on the ERP email module but I see this error when I press check the connection in the ERP.
What I need to know to setup a secure channel between both servers?
Postfix server have a valid working Let's Encrypt certificate.
I can provide the domain privately.