“You are not authorized to send mail on behalf of the specified sending account”

[chosen67]

Below is the workflow for applying for exams

In this workflow for applying for exams, all positions where an email is sent are circled. All emails are sent from the same email address. With the green circles everything works fine, with the red ones the following error message is given:

{

  "status": 403,

  "message": "You are not authorized to send mail on behalf of the specified sending account.\r\nclientRequestId: a7838b06-7119-4bc5-a329-4a412c93eeb6\r\nserviceRequestId: 5a7d7194-c12a-5841-ccd0-dfd43059402b",

  "error": {

    "message": "You are not authorized to send mail on behalf of the specified sending account.",

    "code": "ErrorSendAsDenied",

    "originalMessage": "The user account which was used to submit this request does not have the right to send mail on behalf of the specified sending account., Cannot submit message."

  },

  "source": "outlook-ne.azconn-ne-002.p.azurewebsites.net"

}

This is of course strange, because in one and the same flow an email can be sent at some points and not at other points.

Checked:

- is an identical email address used? -> Yes, a variable has been created for this email address so that this variable can be used everywhere.

- the flow has been tested several times

- I completely logged out of O365 and logged back in a few hours later; then made all connections again

Question: what could be the cause of this?

[creativeopinion]

@chosen67 Do you have permissions to send an email from the email address you've used in your variable? The error that you are getting indicates that you have not been granted permissions to send an email on behalf of that account.

You'll need to ensure you have the appropriate permissions to send an email from the email address you've used in your variable. 

Your flow is pretty complex with many condition branches. Have you confirmed that the emails have been sent at the points you've circled in green?

To confirm that you do have the appropriate permissions to send an email on behalf of the address you've used, can you create a brand new manually triggered flow and add a single action? Add a Send an Email action and insert the same email address you are having issues with in your flow into this action.

Run a test and see if you receive an error as well.

For more flow troubleshooting tips—check out this YT Tutorial: 5 Power Automate Troubleshooting FAQs and Helpful Tips for Creating Better Flows

In this Power Automate tutorial, I explore 5 frequently asked questions that pop up when troubleshooting a flow. If you’d like to to level up your Power Automate flow skills and learn how to troubleshoot your Power Automate flow—this tutorial is for you!

IN THIS VIDEO:

✅ How to troubleshoot a false Condition action result

✅ How to get dynamic content when it isn’t selectable from the list of dynamic content

✅ How to troubleshoot an Apply to Each action that isn’t looping through

✅ How to troubleshoot a skipped Apply to Each action

✅ How to troubleshoot a Filter Query

✅ How to use a SharePoint yes/no column in a Filter Query

✅ How to use Compose actions to troubleshoot a Power Automate flow

✅ How to troubleshoot multiple emails being sent

✅ How to troubleshoot multiple Teams messages being sent

Hope this helps!

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[chosen67]

Thnx @creativeopinion for your reply.

All the emails are send from the same account/email adress. 

The flow has been tested on all points and on all green points an email has indeed been sent (and received) from the same email address. That's what makes this so strange.

Tested again:

result:

[creativeopinion]

@chosen67 The new designer is pretty buggy. Can you try to toggle off the new designer in your original flow and run a test? If that doesn't work. I would recommend creating a brand new flow—toggling off the new designer (before making edits) and rebuilding your flow in the Classic Designer. 

Not saying it'll work ... but worth a try especially since you are able to send emails from the email address as you've confirmed.

[chosen67]

Phew, that's a job. I'm going to try. takes some time. you'll hear from me again later.

[creativeopinion]

@chosen67 Before you do that, in your last flow run, can you confirm the output of the variable that you are using? It could be that your variable has a different value than you are expecting.

[chosen67]

I tested the flow with the variable and it works in the green spots. only the red ones cause a problem

[chosen67]

I am busy recreating the flow in the classic designer. Maybe you can help me before I post a new topic: I don't get a parallel branch in the YES of the control. I need this parallel branch to send reminders to those who need to approve. In the new designer this was not a problem...

If I convert the existing flow from new designer to classic designer, it looks like this:

the do until action is at the bottom of the YES of the control action, there is no parallel branch visible

This is how it looks in the new designer environment:

[creativeopinion]

@chosen67 I'm not sure if I'm understanding your issue ... at the bottom of your original flow where the Do Until action is, I do not see a parallel branch. Could you point out what you are referring to exactly? 

If I compare your original flow in the New Designer to the one in the old designer, this is what I see. Let me know if I'm missing something.

I would recommend that you test out your flow at each stage before you try to build your entire flow and run a test. By testing out in stages it can make it a lot easier to troubleshoot issues in your flow, rather than trying to troubleshoot once your flow is "complete".

[chosen67]

Dear, thank you very much for your response.
I'll try to explain it better:
In the image below you see the part of the flow in the New Designer with the Approval Request.

As long as it has not been approved, the Do until loop must start running. So a parallel branch directly below the True. 
When I switch to the Classic I see the following:

Because there are problems with sending emails from another account ("You are not authorized to send mail on behalf of the specified sending account"), you advised me to recreate the entire flow in Classic. I follow that advice because I see no other solution.

I then arrive at the point below, where I can add an action, an Approval, just like in the New Designer (right image), but I there is no options to add a parallel branch.

So my question is: how can I create a parallel branch, with Approval on one branch and Do Until on the other, so that I can send reminder emails?

[creativeopinion]

@chosen67 I would say that is a bug with the new designer. If you want the Do Until to run if the Approval has not been approved, it needs to run after the approval has been sent and the Do Until action should run based on the outcome of the approval action—not as a parallel branch. That logic wouldn't make sense.