SMTP(postfix) authentication doesn't work

I also tried to use the catatnight/postfix image as the postfix host. I use the mattermost team edition and, thus, adjusted the docker-compose.yml file as follows:

postfix:
  image: catatnight/postfix
  environment:
    - maildomain=my.domain.com
    - smtp_user=user:pass
  expose:
    - 25
db:
  build: db
  volumes:
    - ./volumes/db/var/lib/postgresql/data:/var/lib/postgresql/data
    - /etc/localtime:/etc/localtime:ro
  # uncomment the following to enable backup
  #environment:
  #  - AWS_ACCESS_KEY_ID=XXXX
  #  - AWS_SECRET_ACCESS_KEY=XXXX
  #  - WALE_S3_PREFIX=s3://BUCKET_NAME/PATH
  #  - AWS_REGION=us-east-1
app:
  build: app
  links:
    - db:db
    - postfix
  volumes:
    - ./volumes/app/mattermost/config:/mattermost/config:rw
    - ./volumes/app/mattermost/data:/mattermost/data:rw
    - /etc/localtime:/etc/localtime:ro
web:
  build: web
  ports:
    - "8065:80"
    - "443:443"
  links:
    - app:app
  volumes:
      # This directory must have cert files
    - ./volumes/web/cert:/cert:ro
    - /etc/localtime:/etc/localtime:ro
  environment:
    - MATTERMOST_ENABLE_SSL=false
    - PLATFORM_PORT_80_TCP_PORT=80

@jongsic, can you clearify what you did exactly to deactivate authentication in the catatnight/postfix container?