Shared mailbox permission error

Question

Hi,

I keep receiving the error "This message could not be sent. You are not allowed to send the message on behalf of the specified user "while trying to send an email from the shared mailbox I created.

Answer 1

Dear Alice马,

Good Day! We thank you so much for letting us know that the issue has been resolved after some time, and that information about your new shared mailbox has been propagated throughout all of Microsoft data centers. This is very helpful, and we are grateful to you for being so generous as to share this information with our community so that anybody who finds themselves in a similar situation may use it to resolve their issue.

Your cooperation and kindness are much appreciated. Stay Safe!

Sincerely,

De Paul | Microsoft Community Moderator

Answer 2

Dear Alice马,

Good day! Thank you for posting to Microsoft Community. We are happy to help you.

Based on your description, I understand that you have a query "Shared mailbox permission error".

I have researched about this issue and according to Outlook roaming options - Microsoft Support, if you created a shared mailbox and then try to send a message from it, you might get this error "this message could not be sent. You do not have the permission to send the message on behalf of the specified user", **** this happens when Microsoft 365 encounters a replication latency problem. It should be disappeared in an hour or two, after the information about your new shared mailbox (or added user) has been propagated throughout all of Microsoft data centers. Please wait some time like an hour before trying to send another message and check if any change may happen.

If this is not the case, kindly share the following information with us for further investigation:

1. What version of Outlook are you using? Go to File > Office account > About Outlook. See What version of Outlook do I have? (microsoft.com)
2. Did the issue persist if you Open Outlook in safe mode?
3. Have you tried removing the permission and reassign it again or changing the permission assigned to check if it works?

We look forward to hearing from you; Please understand that our initial reply may not always immediately resolve the issue. However, with your help and more detailed information, we can work together to find a solution. Thank you for your cooperation.

Sincerely,

De Paul | Microsoft Community Moderator

Answer 3

Hi De Paul,

This was resolved for me. I'm not sure what happened when I opened the laptop in the morning, but the issue was gone, and I can now send an email from the shared mailbox.

Thank you for your assistance.