Send an email as a distribution list raise MailboxNotEnabledForRESTAPI error

[Kalio]

Hello everyone,

I hope you can help me, I am encountering an error that I am unable to solve with my PowerAutomate flow.

I want to send an email as a distribution list. My user has the "Send As" delegation on the DL and a PowerAutomate Free license. I chose to use the "Send an email (V2)" module by placing the DL address in the "From" field. The flow always fails with the following error:

{

  "status": 404,

  "message": "L'API REST n'est pas encore prise en charge pour cette boîte aux lettres. Cette erreur peut se produire avec les comptes bac à sable (de test) ou les comptes qui se trouvent sur un serveur de messagerie (local) dédié.\r\nclientRequestId: 18904745-2bd4-4993-812f-e8f44c7283ea\r\nserviceRequestId: ad450537-c47d-8fc0-c16f-6fcc58096061",

  "error": {

    "message": "L'API REST n'est pas encore prise en charge pour cette boîte aux lettres. Cette erreur peut se produire avec les comptes bac à sable (de test) ou les comptes qui se trouvent sur un serveur de messagerie (local) dédié.",

    "code": "MailboxNotEnabledForRESTAPI",

    "originalMessage": "The mailbox is either inactive, soft-deleted, or is hosted on-premise."

  },

  "source": "office365-ne.azconn-ne-002.p.azurewebsites.net"

}

Some additional information:
- This is not a trial tenant, there are many users who have paid Office 365 E3 licenses
- Entire environment is cloud only
- If I assign an Office 365 E3 license to my user, I am able to send an email as the DL from the Outlook application
- No configuration has been changed for several hours and the problem persists

Do you have any idea what could be causing this problem?

Thank you already for your help

[Pstork1 · Accepted solution]

You can't send an email as a DL. It works in Outlook because you are sending the email, its just substituting the DL as the From address.  That won't work in Power Automate because of the way the connector is written.  Also the connector is an Outlook online connector so it requires that the sender have a mailbox in Exchange Online.  The DL doesn't have a mailbox and unless you assign a license to yourself, you don't either. You would need a license to use the action as yourself, just as you do in Outlook.  But the connector isn't written in a way that allows the DL delegation you are using in Outlook. Its just not possible to send an email as a DL in a flow.  You would need at least a shared mailbox.

[Kalio]

Thank you! Since it worked for shared mailboxes, I thought it did for DL as well. I think the easiest way to solve this is to assign me a license then...

[Pstork1]

I know assigning you a license works when you are on the desktop client, but I'm not sure it will work in a flow.  Its worth testing, but I wouldn't be surprised if it still doesn't allow you to send as a DL.