Hi @Walters, Mischelle (US - New York) ,
Agree with Michev that it'd be best to consult WebEx support on this question.
Anyways, from the perspective of Outlook desktop client, normally you should be able to use an add-in as long as you have sufficient permissions ("Full access" and "Send as") .
In case you failed to use the add-in when the shared mailbox is automapped to your primary mailbox, you can ask the Exchange administrator to disable the automapping so that you can add the shared mailbox as a second account in your Outlook. See How to add a shared mailbox as additional account in Outlook (2022 version).
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