SSL Free Certificate Issues [fixed]

[domid]

If you're having issues in using the free certificate issue modal.

BillionMail's core service is mapping ports 5678:5678 and 5679:5679 (HTTP/HTTPS)
BillionMail has its own SSL management but it's not working properly

The Root Cause
BillionMail is trying to serve ACME challenges on port 5678, but Let's Encrypt validates on port 80.
You need to configure nginx to proxy ACME challenge requests to BillionMail.

Solution: Configure Nginx to Proxy ACME Challenges

# Edit the nginx default configuration
sudo nano /etc/nginx/sites-enabled/default

server {
    listen 80 default_server;
    listen [::]:80 default_server;
    
    root /var/www/html;
    index index.html index.htm index.nginx-debian.html;
    server_name _;

    # Proxy ACME challenges to BillionMail
    location ^~ /.well-known/acme-challenge/ {
        proxy_pass http://127.0.0.1:5678;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
    }

    location / {
        try_files $uri $uri/ =404;
    }
}