In order to determine the user who sent a shared mailbox message, we suggest adding a property of sent messages indicating the user who sent it as a delegate; e.g., message.delegateSender or message....
This is such a simple requirement that we want to be able to know the actual user who sent an email through a shared mailbox, as a shared mailbox. Why do we need to find a workaround and/or use Powershell to get this simple information? This should be included, in some way, through Microsoft Graph's `/messages/{id}` endpoint directly.