How to set up a docker container to send mail?

Question

SMTP

Good afternoon.
I have a Django application in a docker container. Nearby in the same place in the Nginx container and Postgres in the same place, all this works together through docker-compose. I want to connect one more service there - to send mail. Tried catatnight/postfix ( https://hub.docker.com/r/catatnight/postfix/ ). Initially just as image in docker-compose.yml, doesn't work.

mail:
    image: catatnight/postfix
    ports:
      - "25:25"
      - "587:587"
    environment:
      - maildomain=cc.example.org
      - [email protected]:1234Qwer
    volumes:
      - ./nginx/letsencrypt:/etc/postfix/certs

There I have letsencrypt certificates, they are *.pem. I cloned the repository, edited assets/install.sh so that the paths to the certificates were written directly, without any $(find /etc/postfix/certs -iname *.key) . Still doesn't work. Django says it can't connect. (No, I didn't forget to write mail in depends_on)
Please help me, all I need to do is just send mail. Don't accept, don't forward, nothing. Send only