I am trying to set the from address in microsoft flow to take the address of another user. But I get the error as
You are not authorized to send mail on behalf of the specified sending account.
How do we solve this?
Yes, I meet the same issue.
MS said "The Outlook connector will be able to send emails only using those email accounts that your credentials have access to. You cannot use the connector to send a mail on behalf of some other user - for obvious security reasons. This behavior and so the error you get are by design."
You can vote here to let product team know our requirement:https://powerusers.microsoft.com/t5/Flow-Ideas/Create-flow-using-quot-Send-as-quot-by-person-s-email-in-quot/idi-p/70316
The person who you are trying to send an email on behalf of must give you permission. "On Behalf Permissions"
You have the ability to keep the account performing the connection to Outlook the same. This may be desired if you do not have extra Office 365 licenses lying around.
From there, you can keep the "Send As" address that you would like (i.e. a Distribution List), and then just grant permission to the workflow account (delegating) to allow it to send emails.