There is no GUI for this.
You can run docker logs postfix
This server allows anything on the LAN to send via 192.168.1.240 port 25 with no authentication which is then relayed via AWS SES.
Docker Compose:
version: '3.8'
services:
postfix:
image: juanluisbaptiste/postfix
container_name: postfix
ports:
- "25:25"
environment:
SMTP_SERVER: email-smtp.ap-southeast-2.amazonaws.com
SMTP_USERNAME: redacted
SMTP_PASSWORD: redacted
SERVER_HOSTNAME: homeassistant
restart: always