Using shared mailbox on mobile device with Exchange 2019 On-premise.

Question

Hello!

Maybe somebody can help me with my strange situation.

Deployment:

1. On-premises 2019 Exchange server (15.02.1544.011) installed on Windows Server 2019 fully updated (and restarted) today.
2. Regular User mailbox called user
3. Shared mailbox called shared_mailbox
4. Permission for user to user shared_mailbox :
   1. Add-MailboxPermission shared_mailbox -User user -AccessRights FullAccess -AutoMapping $false
   2. Add-ADPermission -Identity shared_mailbox -User user -AccessRights ExtendedRight -ExtendedRights "Send As"

Problem:

Everything works fine with desktop outlook client and OWA. User can send message from itself and send as shared_mailbox.

User can add and use without any error his own mailbox from outlook for iOS.

But user cant send message from shared_mailbox using outlook for iOS.

I can't follow this manual, because there is no option "Add a shared mailbox" in outlook app.

https://support.microsoft.com/en-us/office/add-a-shared-mailbox-to-outlook-mobile-f866242c-81b2-472e-8776-6c49c5473c9f

The error text:

We couldn't deliver your message.
Original message details
Created date: 7/2/2024 10:31:50 AM
Sender address: shared_mailbox@contoso.com
Recipient addresses: recipient@fabrikam.com
Subject: Test


Technical details
EasSendFailedPermanentException: An EAS Send command failed: The EAS command failed with Status MailSubmissionFailed, Code ='120' and HttpStatus OK. --> The EAS command failed with Status MailSubmissionFailed, Code ='120' and HttpStatus OK.
Failure code: a056

And error message exist only in mobile client, it does not sync to server (and doesn't appear in desktop outlook). So, I suggest, the message doesn't even uploads to server.

Any ideas?

Thanks in advance.

Answer 1

Looks like the issue is more related to Outlook for mobile. Please kindly understand that the Outlook tag here we mainly focus on general issues about Outlook desktop client. In order to better solve your problem, it's suggested to post your issue on this dedicated forum for Outlook for Mobile for more professional help.