Use "Docker Compose Empty" in Coolify -> Add your API keys for AWS SES and GitHub + Add the traefik-certs-dumper in the settings and you're ready to roll

compose-useSend-coolify.yaml

services:
  postgres:
    image: 'postgres:16'
    environment:
      - 'POSTGRES_USER=${SERVICE_USER_POSTGRES}'
      - 'POSTGRES_PASSWORD=${SERVICE_PASSWORD_POSTGRES}'
      - 'POSTGRES_DB=${SERVICE_DB_POSTGRES:-usesend}'
    healthcheck:
      test:
        - CMD-SHELL
        - 'pg_isready -U $${POSTGRES_USER} -d $${POSTGRES_DB}'
      interval: 5s
      timeout: 20s
      retries: 10
    volumes:
      - 'usesend-postgres-data:/var/lib/postgresql/data'
  redis:
    image: 'redis:7'
    volumes:
      - 'usesend-redis-data:/data'
    command:
      - redis-server
      - '--maxmemory-policy'
      - noeviction
    healthcheck:
      test:
        - CMD
        - redis-cli
        - PING
      interval: 5s
      timeout: 10s
      retries: 20
  usesend:
    image: 'usesend/usesend:latest'
    expose:
      - 3000
    environment:
      - SERVICE_URL_USESEND_3000
      - 'DATABASE_URL=postgresql://${SERVICE_USER_POSTGRES}:${SERVICE_PASSWORD_POSTGRES}@postgres:5432/${SERVICE_DB_POSTGRES:-usesend}'
      - 'NEXTAUTH_URL=${SERVICE_URL_USESEND}'
      - 'NEXTAUTH_SECRET=${SERVICE_BASE64_64_NEXTAUTHSECRET}'
      - 'AWS_ACCESS_KEY=${AWS_ACCESS_KEY:?}'
      - 'AWS_SECRET_KEY=${AWS_SECRET_KEY:?}'
      - 'AWS_DEFAULT_REGION=${AWS_DEFAULT_REGION:?}'
      - 'GITHUB_ID=${GITHUB_ID:?}'
      - 'GITHUB_SECRET=${GITHUB_SECRET:?}'
      - 'REDIS_URL=redis://redis:6379'
      - 'NEXT_PUBLIC_IS_CLOUD=${NEXT_PUBLIC_IS_CLOUD:-false}'
      - 'API_RATE_LIMIT=${API_RATE_LIMIT:-1}'
      - HOSTNAME=0.0.0.0
      - 'SMTP_HOST=${SMTP_HOST-send.example.com}'
      - 'SMTP_USER=${SMTP_AUTH_USERNAME-usesend}'
    depends_on:
      postgres:
        condition: service_healthy
      redis:
        condition: service_healthy
    healthcheck:
      test:
        - CMD-SHELL
        - 'wget -qO- http://usesend:3000 || exit 1'
      interval: 5s
      retries: 10
      timeout: 2s
  smtp-server:
    container_name: usesend-smtp-server
    image: 'usesend/smtp-proxy:latest'
    volumes:
      - '/data/coolify/certs/send.example.com:/data/certs:ro'
    environment:
      - SMTP_AUTH_USERNAME=usesend
      - USESEND_BASE_URL=https://send.example.com
      - USESEND_API_KEY_PATH=/data/certs/key.pem
      - USESEND_API_CERT_PATH=/data/certs/cert.pem
    expose:
      - 25
      - 587
      - 2587
      - 465
      - 2465
    ports:
      - '25:25'
      - '587:587'
      - '2587:2587'
      - '465:465'
      - '2465:2465'
    labels:
      - 'traefik.tcp.routers.smtp.rule=HostSNI(`*`)'
      - traefik.tcp.routers.smtp.entrypoints=smtp
      - traefik.tcp.routers.smtp.service=smtp
      - traefik.tcp.services.smtp.loadbalancer.server.port=25
      - 'traefik.tcp.routers.smtps.rule=HostSNI(`*`)'
      - traefik.tcp.routers.smtps.tls.passthrough=true
      - traefik.tcp.routers.smtps.entrypoints=smtps
      - traefik.tcp.routers.smtps.service=smtps
      - traefik.tcp.services.smtps.loadbalancer.server.port=465
      - traefik.tcp.services.smtps.loadbalancer.proxyProtocol.version=2
    healthcheck:
      test:
        - CMD-SHELL
        - "echo QUIT | nc -w 5 localhost 25 | grep -q '^220'"
      interval: 30s
      timeout: 10s
      retries: 3

I originally started messing with Traefik labels at the server level, but it turned out I didn’t need to. I followed Aldert’s lead making sure that the server’s certificates could be available for the relay to use by appending the following to the Traefik configuration in
Server → Proxy → Configuration

traefik-certs-dumper:
  image: ghcr.io/kereis/traefik-certs-dumper:latest
  container_name: traefik-certs-dumper
  restart: unless-stopped
  depends_on:
    - traefik
  volumes:
    - /etc/localtime:/etc/localtime:ro
    - /data/coolify/proxy:/traefik:ro
    - /data/coolify/certs:/output

IMPORTANT

traefik-certs-dumper could not generate the certificate in time so I restart the container and it will create the new certificaes

$ docker restart traefik-certs-dumper

For more info check:

• https://docs.usesend.com/self-hosting/overview
• https://mattstein.com/thoughts/coolify-unsend/
• https://aldertvaandering.com/blog/setting-up-stalwart-on-coolify