Send Email with Azure/M365

azmail.py

#!/usr/bin/env python3
from argparse import ArgumentParser
import json
import sys

import requests

# Retrieve an access token via the device code flow:
# roadtx auth --tokenfile ~/.cache/azmail.json --resource https://outlook.office.com --client d3590ed6-52b3-4102-aeff-aad2292ab01c --tenant contoso.com --device-code

# Refresh an existing access token:
# roadtx auth --tokenfile ~/.cache/azmail.json --resource https://outlook.office.com --client d3590ed6-52b3-4102-aeff-aad2292ab01c --tenant contoso.com --refresh-token "$(jq -r .refreshToken ~/.cache/azmail.json)"

# Send an email:
# azmail -t ~/.cache/aztoken.json -s 'Test 1' -b 'Hello world!' -r john.doe@contoso.com

# docs:
# - https://learn.microsoft.com/en-us/graph/api/user-sendmail
# - https://learn.microsoft.com/en-us/previous-versions/office/office-365-api/api/version-2.0/mail-rest-operations#SendMessages

# I could not find a public client with the Mail.Send permission on graph.microsoft.com.
# Therefore I had to fall back to the deprecated outlook.office.com API for now.
# See e.g. https://github.com/secureworks/family-of-client-ids-research/blob/main/scope-map.txt

#ENDPOINT = 'https://graph.microsoft.com/v1.0/me/sendMail'
ENDPOINT = 'https://outlook.office.com/api/v2.0/me/sendmail'


def main() -> None:
    entrypoint = ArgumentParser()
    entrypoint.add_argument('-t', '--token', required=True)
    entrypoint.add_argument('-s', '--subject', required=True)
    entrypoint.add_argument('-b', '--body', required=True)
    entrypoint.add_argument('--content-type', choices=('text', 'html'), default='text')
    entrypoint.add_argument('-r', '--recipient', dest='recipients', action='append', required=True)
    opts = entrypoint.parse_args()

    if opts.token.startswith('eY'):
        token = opts.token
    else:
        with open(opts.token) as file:
            data = json.load(file)
        token = data['accessToken']

    response = requests.post(
        ENDPOINT,
        headers={'Authorization': f'Bearer {token}'},
        json=dict(
            Message=dict(
                Subject=opts.subject,
                Body=dict(
                    ContentType=opts.content_type,
                    Content=opts.body,
                ),
                ToRecipients=[dict(emailAddress=dict(address=address)) for address in opts.recipients],
            ),
            SaveToSentItems=True,
        ),
    )
    if response.status_code != 202:
        data = response.json()
        print(data['error']['message'], file=sys.stderr)
        exit(1)


if __name__ == '__main__':
    main()