We want to send email to logged in users in our Drupal application. We are authenticating using AAD and our site is hosted in Azure app service.
we have a generic service account with a mailbox attached and we would like to notify the logged in users in case of any event using MS graph API and O365 connections.
Can we please get some guidance in this respect.
You can use the Graph API to send emails from your service account. Where you are going to have a problem is with identifying logged in users. An AAD token will be valid for your site even if the user originally signed in somewhere else, so logging signins isn't foolproof. Unless your users specifically sign out, the token will also be valid past when they stop using the site.
If you wanted to go down this road, then doing some logging of user actions and then sending the email to users that have been active within X amount of time might be an option.
If your goal is to notify users and you don't need an email specifically, then you might want to looking into using websockets or something similar to send notifications to the users within their browser.