“Send on Behalf” not showing correctly in New Outlook but works in Classic Outlook

Dear @Pralhad Rijal,

Thank you for posting your question in the Microsoft Q&A forum.

Based on your description, I understand you've followed the correct steps, but the "send on behalf" feature isn't displaying as expected. According to my research, many users also have this issue, therefore, this issue might be a known display inconsistency in New Outlook.

Firstly, to confirm whether a message was truly sent “on behalf of” another user, the most reliable way is to check the email headers: Open Outlook > Open the email you received > Click the three dots (…) in the top-right corner > Select View > View message details > A window will open with the full headers. Then, look for From and Sender information again, does it appear there?

Moreover, here are some steps I recommend you try again:

Step 1/ I recommend you try to re-add the permission again in Classic Outlook. For more information: Share and access another person's mailbox or folder in Outlook and Allow messages to be sent on your behalf when sharing a folder or mailbox

Step 2/ Have you checked to ensure that you only have "send on behalf" permissions and not "send as" permissions for the mailbox? If both permissions are assigned, "send as" will take precedence.

• Sometimes, removing and re-adding the "send on behalf" permissions can resolve the issue. You can do this in the Exchange Admin Center (EAC) by removing yourself from the "send on behalf" list and then adding yourself back.
• For more information, please refer to Manage permissions for recipients in Exchange Online

Step 3/ Have you tried sending an email using the "send on behalf" feature from the Outlook Web App? This can help determine if the issue is specific to the Outlook client. To do this:

• Log in to the mailbox via Outlook Web App.
• Compose a new message.
• Click on "Options" and ensure "Show From" is checked.
• Click on the "From" field, choose "Other email address," and type in the shared mailbox address.
• Send a test email and check if the "on behalf of" information appears correctly.

Step 4/ When selecting the "From" address in Outlook, ensure you are choosing the address from the Global Address List (GAL) rather than typing it manually.

Note: Please understand that as forum moderator, my primary goal is to provide helpful guidance and support through general troubleshooting steps. While I don’t have access to internal systems or test devices required to resolve backend issues, I truly appreciate your understanding of these limitations. I genuinely hope the information I share helps guide you in the right direction, and I'm always here to assist as much as I can within my scope.   

I hope this information is helpful. Please follow these steps and let me know if it works for you. If not, we can work together to resolve this. If I misunderstand anything, please feel free to reach out.

Please understand that our initial response does not always resolve the issue immediately. However, with your help and more detailed information, we can work together to find a solution.

Thank you for your patience and your understanding. If you have any questions, please feel free to reach out.

I'm looking forward for your reply.

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