- multiple domains via ENV ADD_DOMAINS supported (ADD_DOMAINS=domain1.tld,domain2.tld,...)
- added check for mysql availability so container does not start until mysql is ready
- syslog only logs mail.* to stdout, no mount on /var/log/mail needed
- supervisor only logs syslog to stdout, so all relevant mail logs are in stdout
- var replacement with sed was replaced by envtpl for better readability
- all ENV vars are now initialised in startup script rather than Dockerfile
- letsencrypt certs from https://github.com/JrCs/docker-letsencrypt-nginx-proxy-companion can be used
- fixed some permission issues with dovecot (ignore mountpoints did not work since conf file replacement was done afterwards so there were errors)
- changed opendkim and opendmarc from socket to ip because of weird permissions issues (opendkim did not work when the postfix user was in the opendkim group)