Learn how to allow your users to access Microsoft 365 from ExMixedFolders or EEAttachments.
Depending on the setting made in your Azure portal under Enterprise applications=>Consent and permissions, you may have to allow the user whose mailbox is to be accessed to use the application to log on to Microsoft 365.
In the following, we assume that you do not have the "Allow user consent for apps" option active (all users can consent to access the organization's data for each app).
So if an unauthorized user attempts to log in using either program, they will be prompted that "admin consent" is required.
To give this consent on a fast track basis, the admin can log in to the application once and will be given the option to "consent on behalf of their organization".
If this has been activated, the desired user can then now log on to Microsoft 365 with the application.
Since the application is now listed in the Azure portal under enterprise applications, the administrator can restrict it to specific users or groups. (e.g. under Properties => "Assignment required" and then add the corresponding users under "Users and Groups")
Another way to grant access for apps is to configure the "Admin consent workflow" under Enterprise applications => Manage => User settings. Here you can specify that administrators receive emails to approve the app and can then decide whether the corresponding user receives approval.