Do Outlook web add-ins work in OWA (Exchange 2016 or 2019) for Shared-Mailboxes?

[neville-jones]

Environment

• Platform: Office on the web
• Host: Outlook
• Exchange environment: Exchange 2016 or 2019 - On-Premise only, not hybrid
• Operating System: Windows or others
• Browser (if using Office on the web): any

Scenario

Our customer is using our Outlook web add-in in an on-premise Exchange environment (2016 and 2019 Exchange). The add-in is working as expected from an end-user's primary mailbox in Outlook on the Web (or OWA). Many of their end-users also send and receive messages from a shared mailbox. They have found our Outlook web add-in is not available or operable (it also implements functionality at the on-send event, but that is not functioning either) when used from the shared mailbox (accessed via the "Open another mailbox" option so is in a separate tab to the primary mailbox).

The functionality seems consistent with the table published at https://learn.microsoft.com/en-us/office/dev/add-ins/outlook/delegate-access?tabs=web%2Cxmlmanifest#supported-clients-and-platforms - web browser + Exchange 2016/2019 + shared mailbox = Not applicable (which we think means is not supported?).
Our Outlook add-in does operate at the on-send event in a Web browser if it is an Exchange Online environment which is again consistent with the table.

Our Outlook web add-in does operate successfully if used from the primary mailbox in the "Shared Folder" mode but the customer would prefer to use the "Shared Mailbox" mode as their end-users are familiar with that and avoids errors with the incorrect From address being used for messages sent from the shared mailbox.

The customer has raised a ticket with Microsoft support and it is under Microsoft Case Number: 2501080050002252 ; Microsoft support advised that the scenario is supported, exert of message from our customer:

It's not quite right, because we have open a Microsoft case for the question: "Working Web-Add-Ins in OWA (Exchange2016) for Shared-Mailboxes?". And Microsoft said: yes. Microsoft said also the Developer from the ___ plug-in should open a support request at Office-Dev-Team to find out the problem or limitations.

So we are trying to resolve this conflicting advice from Microsoft - are Outlook web add-ins operable in a web browser when accessing a shared mailbox in its own browser tab, in an Exchange 2016 or 2019 environment?

[github-actions]

Here are some similar issues that might help you. Please check if they can solve your problem.

• [Outlook] Outlook add-in not enabled for shared mailbox in Windows Outlook 2016 client #160

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Possible solution (Extracted from existing issue, might be incorrect; please verify carefully)

This question has been answered here: #159

Reference:

• [Outlook] Outlook add-in not enabled for shared mailbox in Windows Outlook 2016 client #160 (comment)

[patilganesh-msft]

Hi @neville-jones,

As mentioned in the documentation: https://learn.microsoft.com/en-us/office/dev/add-ins/outlook/delegate-access?tabs=web%2Cxmlmanifest#supported-clients-and-platforms, add-ins will not work as expected if opened in a new tab. So, it is expected.

[neville-jones]

We do feel the table and documentation at the page https://learn.microsoft.com/en-us/office/dev/add-ins/outlook/delegate-access?tabs=web%2Cxmlmanifest#supported-clients-and-platforms requires more clarity to avoid confusion here.

In particular, the row for "Web browser (classic Outlook UI)" should be split into two rows - one row for Shared mailboxes which would have "Not applicable" for Exchange Online and then "Not supported" for Exchange 2019 and Exchange 2016 and the next row for Shared folders which would have "Not applicable" for Exchange Online and then "Supported" for Exchange 2019 and Exchange 2016.

We will report this as a documentation issue.