Tag/version of Container Images
latest as of today (34b5c3af84cc)

My mail server does support both SSL/TLS & STARTTLS flawlessly in all sorts of configurations.

To Reproduce

services:
  web:
    image: maxking/mailman-web
    environment:
      - SMTP_HOST=<mail.example.com>
      - SMTP_PORT=465
      - SMTP_HOST_USER=<user>
      - SMTP_HOST_PASSWORD=<pass>
      - SMTP_USE_SSL=True
      - SMTP_USE_TLS=False

$ docker-compose exec mailman-web /opt/mailman-web/manage.py sendtestemail hostmaster@example.com

Hangs.

services:
  web:
    image: maxking/mailman-web
    environment:
      - SMTP_HOST=<mail.example.com>
      - SMTP_PORT=587
      - SMTP_HOST_USER=<user>
      - SMTP_HOST_PASSWORD=<pass>
      - SMTP_USE_TLS=True
      - SMTP_USE_SSL=False

$ docker-compose exec mailman-web /opt/mailman-web/manage.py sendtestemail hostmaster@example.com

Works.

Logs

I couldn't find any error message in any of the logs in /opt/mailman-web-data/logs pertaining to SMTP, as such I have no more information.