You may check whether you can see shared mailbox emails using the Outlook Web App. For your reference: https://support.microsoft.com/en-us/office/open-and-use-a-shared-mailbox-in-outlook-d94a8e9e-21f1-4240-808b-de9c9c088afd#OfficeVersion=Outlook_on_the_web
Messages cannot be viewed in the shared mailbox
Alen_Erased
100
Reputation points
How do I use a shared mailbox? I added a shared mailbox in the admin center, and then the name of the contributed game appeared in my desktop client, but when I sent an email to this mailbox, I couldn't see the mail in the shared mailbox. How can I solve this problem?