nginx + php7.0 + WordPress4.8.3 + Lang:Japanese
Error message mail() is not allowed by hosting server.
English is no ploblem, WordPress can send mal and mailcatcher can catch mail.
Mailcatcher WebUI listen port 1080 default. Docker run -p 1080:1080 I can access localhost:1080,without explicit open port in Dockerfile.
Probably, mailcacther can open port, because supervisord kick mailcather process with root priviledges.