Cannot use Office 365 for SMTP

Developer help
1

I am having a very difficult time trying to configure Ghost to send e-mail via Office 365. I keep getting a “Send As” denied exception. Is Ghost not using the mail__from environment variable?

I tested probably 20 different configurations, including TLS and Secure options, but continue getting the same message. I know that SMTP is working as I can use send an e-mail via other services using the same account + credentials. It just seems like Ghost is trying to use something other than my mail__from setting.

Any help would be greatly appreciated.

Issue: “Send as” exception denied from Ghost 4.2.2

Ghost URL: https://blog.gallagher.app
Ghost Version: 4.2.2

How was Ghost installed?: Using Docker on Ubuntu 20.04 and Docker compose
Node version: 14.16.1
Database: MariaDB
Errors in console (stdout):

STOREDRV.Submission.Exception:SendAsDeniedException.MapiExceptionSendAsDenied

Steps to reproduce: Setup Office 365 SMTP?

docker-compose.yml:

version: "3"

volumes:
  ghost-db-data:
    external: true
  ghost-data:
    external: true
  ghost-content:
    external: true
  ghost-required:
    external: true

networks:
  backend:
  traefik:
    external: true

services:  
  ghost:
    image: ghost:latest
    container_name: ghost-blog
    volumes:
      - ghost-required:/var/lib/ghost/content
      - ghost-data:/var/lib/ghost
      - ghost-content:/var/lib/ghost-content
    environment:
      - url=https://blog.gallagher.app
      - logging__path=/var/lib/ghost-content/logs
      - logging__transports=["stdout", "file"]
      - logging__level=debug
      - logging__rotation__enabled=true
      - logging__rotation__count=15
      - logging__rotation__period=1d
      - mail__transport=SMTP
      - mail__from=blog@gallagher.app
      #- mail__options__service=O365
      - mail__options__host=smtp.office365.com
      - mail__options__port=587
      - mail__options__auth__user=blog@gallagher.app
      - mail__options__auth__pass=**removed**
      - database__client=mysql
      - database__connection__host=ghost-db
      - database__connection__user=ghostdb
      - database__connection__password=**removed**
      - database__connection__database=ghostdb
      - GHOST_CONTENT=/var/lib/ghost-content/
      - VIRTUAL_HOST=blog.gallagher.app
      - VIRTUAL_PORT=2368
    networks:
      - backend
      - traefik
    ports:
      - "8040:2368/tcp"
    depends_on:
      - "ghost-db"
    restart: unless-stopped
    labels:
      - 'traefik.enable=true'
      - 'traefik.http.routers.ghost.rule=Host(`blog.gallagher.app`)'
      - 'traefik.http.routers.ghost.entrypoints=https'
      - "traefik.http.routers.ghost.tls=true"
      - 'traefik.http.routers.ghost.tls.certresolver=letsencrypt'
      - 'traefik.http.routers.ghost.tls.domains[0].main=blog.gallagher.app'
      - 'traefik.http.services.ghost.loadbalancer.server.port=2368'

  ghost-db:
    image: mariadb:latest
    container_name: ghost-db
    volumes:
      - ghost-db-data:/var/lib/mysql
    environment:
      - MYSQL_ROOT_PASSWORD=**removed**
      - MYSQL_DATABASE=ghostdb
      - MYSQL_USER=ghostdb
      - MYSQL_PASSWORD=**removed**
    networks:
      - backend
    restart: unless-stopped