Unable to send as using shared mailbox

Question

Hello,

Multiple users in my organization are unable to send emails as shared mailbox address, they always had the correct send as shared mailbox permissions and still have them, as I have double checked.

This starts with user getting the following error
"The following recipient(s) cannot be reached:

   Ali Mirza on 9/5/2023 1:12 PM 

        This message could not be sent. You do not have the permission to send the message on behalf of the specified user.  

__________________________________________________

Diagnostic information for administrators:

________________________________________________

Error is [0x80070005-0x000004dc-0x00000524]...."

I have tried updating outlook from file>office account>update Office. removing and adding users outlook profile back to outlook. tried running the  Microsoft Support and Recovery Assistant with no luck.

the only thing that seems to fix the send as issue the first time is by switching to New Outlook, this then would work for a short time and then start giving the following message,
Couldn't send this message on new outlook, with More details not giving much information
"The Original message can't be shown right now. It will be included when this message is sent"

"This message can't be sent right now. Please try again later."

Is there a way to fix this?

These are the error messages on New Outlook https://learn-attachment.microsoft.com/api/attachments/413c8037-a1dd-4825-b149-ac905e3ef11f?platform=QnA"https://learn-attachment.microsoft.com/api/attachments/d07a96c4-2ede-4fc7-9626-3c4edfe51192?platform=QnA" title="filestore.community.support.microsoft.com" rel="ugc nofollow">

Answer 1

Hello AliM112,

Thank you for posting this case in Microsoft Community!

As mentioned, you could not send as using shared mailbox in New Outlook with error message. I would like to cooperate with you working on this case.

T

o clarify this case, please help to collect following information for further analysis:

• Have you tried to send us using shared mailbox in Legacy Outlook if working or not? If getting the same case?
• Please note: If this issue only happen via **New Outlook,**please****contact New Outlook for Windows Teamvia clicking Help > Support or Contact support and provide feedback within the new Outlook for Windows
• If shared mailbox showing in your Outlook normally after permission set up later?
• Have you tried to access Outlook Web and use Open another mailboxoptions to access shared mailbox with testing if working? Open and use a shared mailbox in Outlook Web App

If working fine via Outlook web as well as Legacy Outlook, for my suggestion, you may try following workaround as shared:

1. Firstly, you may use EXO Power Shelland get shared mailbox permission details as below captured:

2. For permission error, if you created a shared mailbox and then try to send a message from it, you might get this:

This message could not be sent. You do not have the permission to send the message on behalf of the specified user.

This message appears when Microsoft 365 is experiencing a replication latency issue. It should go away in an hour or so, when the information about your new shared mailbox (or added user) is replicated across all of our data centers. Wait an hour and then try again to send a message.

Resolve issues with shared mailboxes

3. If still not working, please try to Office 365 admin center to remove your permission of shared mailbox.

A. Then only add one permission(Send as or Send on behalf) to your email account via Shared Mailbox settings.

**B.**After that, please re-configure your Outlook profile and wait for at least one hour(60 minutes) if shared mailbox showing in Outlook normally.

Steps:Create an Outlook profile - Microsoft Support

(1). In Outlook, select File > Account Settings > Manage Profiles

(2). Choose Show Profiles > Add.

(3). In the Profile Name box, type a name for the profile, and then choose OK.

C. Finally, after more than one hour, you may test in Legacy Outlookas well as New Outlook again.

If you need further assistance, please feel free to let me know, I will keep assisting you.

Your understanding and patience will be appreciated.

Thank you!

Answer 2

Same problem here. Could not send mails with mail alias from external provider like gmail. I noticed that the synchronisation of the external providers did not work anymore "error at synchronization". So i checked the credentials and settings. These are correct and working. So maybe there is a general problem with that feature in relation to the complete reorganisation of the new outlook stuff?!

I'm using Outlook Desktop App (x64) from Office-Suite and the new Outlook OWA App and tried in in the webbrowser unter outlook.com. Everywhere the same problem...

Answer 3

hello,

look here: https://answers.microsoft.com/en-us/outlook_com/forum/all/issue-with-new-outlook-desktop-app-with-shared/e0c5ed5b-1aba-473b-99cc-57c7687e3aa2?page=2&messageId=0017aa02-b4a6-404d-a05d-d12600fa7a9e

if I interpret your problem correctly, it is the same case