Send an email as a shared mailbox (the From address is the shared mailbox).

The signed-in identity needs Send As rights on the shared mailbox (an Exchange Online admin action). Sending through the mailbox's own sendMail endpoint makes the From header the shared mailbox address, not the sender's.

Permissions

Requires delegated Mail.Send.Shared (or app Mail.Send).

Reference

• https://learn.microsoft.com/en-us/graph/api/user-sendmail

View source

from __future__ import annotations

import argparse

from office365.graph_client import GraphClient
from tests.settings import client_id, password, tenant, user_principal, username


def main() -> None:
    parser = argparse.ArgumentParser(description="Send mail as a shared mailbox")
    parser.add_argument("--mailbox", required=True, help="shared mailbox UPN, e.g. support@contoso.com")
    parser.add_argument("--to", action="append", default=[], help="recipient (repeatable; default: the test user)")
    parser.add_argument("--send", action="store_true", help="actually send (otherwise just report the plan)")
    args = parser.parse_args()

    recipients = args.to or [user_principal]
    if not args.send:
        print(f"Would send from {args.mailbox} to {', '.join(recipients)}; re-run with --send.")
        return

    client = GraphClient(tenant=tenant).with_username_and_password(client_id, username, password)
    client.users[args.mailbox].send_mail(
        subject="Sent from a shared mailbox",
        body="This message was sent via office365-rest-python-client.",
        to_recipients=recipients,
    ).execute_query()
    print(f"Email sent from {args.mailbox} to {', '.join(recipients)}.")


if __name__ == "__main__":
    main()

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