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We have an On-Premise Exchange 2019 installed on a server and Monthly Enterprise Channel M365 Outlook installed on client machine.

The problem is that all the office.js add-ins which are installed using a manifest file onto the on-premise Exchange server are not loaded in M365 Outlook, no ribbon button and no button below the selected email's header.

In OWA or Outlook 2016 it is working correctly, the issue is only with M365 Outlook. Based on the supported mailbox requirement set, there shouldn't be a problem.

Is there a limitation that manually installed add-ins on an on-premise Exchange server are not loaded inside M365 Outlook?

Thanks

Eugene Astafiev
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Gyula Fekete
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  • Can you give details on the Outlook version numbers where it's working and not working? Are you using same on-prem account to check in both Outlook 2016 and Outlook M365 ? Which platform are you using for Outlook client win32 or mac? – Outlook Add-ins Team - MSFT Aug 02 '23 at 09:47

1 Answers1

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There could be two possible cases:

The problem is that all the office.js add-ins which are installed using a manifest file onto the on-premise Exchange server are not loaded in M365 Outlook, no ribbon button and no button below the selected email's header.

Sometimes you need to wait until changes are applied to client applications. For example, users might need to relaunch Microsoft 365 to view the add-in icon on the app ribbon. Outlook add-ins can take up to 24 hours to appear on app ribbons. See Deploy add-ins in the Microsoft 365 admin center for more information on that.

Based on the supported mailbox requirement set, there shouldn't be a problem.

There is a server-supported requirement set and the client-supported requirement set. You need to make sure that both of them support the requirement set specified in the add-in manifest. If any side doesn't support the requirement set your add-in will not be running/appearing.

Eugene Astafiev
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  • Thanks for the feedback. This is what we have in manifest: ... ... "VersionOverridesV1_0" .... VersionOverridesV1_1 .... So there shouldn't be a problem with Exchange 2019 and Monthly M365 Outlook – Gyula Fekete Jul 26 '23 at 07:49
  • Also it is now more days since this was detected. Not clear why is it working in Outlook 2016 and not in Outlook M365? – Gyula Fekete Jul 26 '23 at 07:55