No new certificate (Let's Encrypt) for my mail server

Good morning,
I see only 2 ways:
A)

  • special firewall rules that opens port 80 for 30 minutes and disable location filter for that time
    … I saw something like this … but can’t find it again
    … now found it: Let's Encrypt - Location filter and firewall rule (command) - #3 by pablo78
    … I began this … and it’s very tedious to add all countries to the list
    Is there a way to ADD ALL COUNTRIES with 3…4 clicks to the list??

B)

  • install and configure Lets Encrypt at IPFire ?
    … this would be the better way - we have to search …