have you done any settings change in languages?

you should run ansible playbooks again. also you could just try to remove the line from nginx config on the server.

try to remove listen [::]:80; line in nginx.conf template (https://github.com/LemmyNet/lemmy-ansible/blob/main/templates/nginx.conf)

maybe you could create a community and post guides there.

you can define it as environment variables in https://github.com/LemmyNet/lemmy-ansible/blob/main/templates/docker-compose.yml i.e mine contains these lines:

  postfix:
    image: mwader/postfix-relay
    environment:
      - POSTFIX_myhostname=group.lt
      - POSTFIX_inet_protocols=ipv4
      - POSTFIX_smtp_sasl_auth_enable=yes
      - POSTFIX_smtp_sasl_password_maps=static:smtp_username:smtp_password
      - POSTFIX_smtp_tls_security_level=may
      - POSTFIX_smtp_sasl_security_options=noanonymous
      - POSTFIX_relayhost=sendgridsmtpserver:serverport
      - OPENDKIM_DOMAINS=group.lt
    restart: "always"

you should be able to use any mail gateway that supports smtp. one way to do it is to configure postfix to use sendgrid as relayhost - https://docs.sendgrid.com/for-developers/sending-email/postfix