IdStory Identity Manager

This image also works completely fine. It stashes mail in /tmp/fakemail on the host where it can be viewed. I think this is totally fine as /tmp gets cleaned up as needed.

Working minimal compose file:

version: '2.1'

services:

  # Build from local "Dockerfile" file
  local-example:
    build:
      context: .
    image: munkyboy/fakesmtp
    volumes:
      - /tmp/fakemail:/var/mail
    ports:
      - "2525:25" 
    restart: always

The fakeSMPT works perfectly, good choice. Some tests from core use this. It is singleton but for tests it is enough:
https://github.com/bcvsolutions/CzechIdMng/blob/develop/Realization/backend/core/core-test-api/src/main/java/eu/bcvsolutions/idm/test/api/AbstractNotificationTest.java