Joplin Server 2.2.6 - Email Settings

This works with icloud custom email domains as well.

settings with my info removed

environment: 
      - MAILER_ENABLED=1
      - MAILER_HOST=smtp.mail.me.com 
      - MAILER_PORT=587 
      - MAILER_SECURITY=1
      - MAILER_AUTH_USER=user@domain
      - MAILER_AUTH_PASSWORD=redacted
      - MAILER_NOREPLY_NAME=joplinserver
      - MAILER_NOREPLY_EMAIL=no-reply@domain

Note that icloud only gives you 3 "aliases" per custom domain, so choose them wisely.