This is a sample script for sending Outlook emails using Microsoft account with Google Apps Script. Before you use this script, please install OnedriveApp which is Google Apps Script library. And, please authorize your Microsoft account for using Microsoft Graph API.
The author of this contribution, Kanshi Tanaike, always comes up with interesting Google Apps Script solutions. This particular example uses a OnedriveApp library which makes it easy to interact with other part of the Microsoft Graph API expanding the possibilities.