smtpd-proxy.yml

smtpd-proxy:
  # interface address smtpd-proxy will listen-to
  # use *:1025 to bind on localhost,
  # or 0.0.0.0:1025 to  listen on all interfaces
  listen: 127.0.0.1:1025

  # host identification
  ehlo: localhost

  # authentication.
  username: user
  password: secret
  # is_anon_auth_allowed: true

  # TLS cert and key.
  # server-cert: server.crt
  # server-key: server.key

  upstream-servers:
    - type: log
      weight: 10

    - type: smtp
      weight: 10
      settings:
        # host:port to conect to
        addr: smtp.mailtrap.io:2525
        # host identification, optional, needed for auth
        host: smtp.mailtrap.io

        # Auth methods available: login, plain, cram-md5, anon
        auth: plain
        username: 8333f344d8884e
        password: secret

    - type: ses
      weight: 1000
      settings:
        # AWS credentials, key ID
        aws_access_key_id: amz-key-1
        # AWS credentials, access secret key
        aws_secret_access_key: amz-**-secret
        # AWS API endpoint, e.g. localstack
        # endpoint: http://localhost:4566
        # region: us-east-1