Only Allow Corporate Email in Outlook Desktop app

[msage2000]

Hi,

Is there a way to only allow corporate emails in the Outlook app on company assets?

I've tried implementing a GPO and that works for blocking non-corporate emails, however, it blocks users from using shared mailboxes (shared mailboxes must be allowed for business ops).

I've also tried to prevent personal Microsoft accounts from using MAPI but that was ineffective in blocking the non-corporate emails.

Furthermore, users must still be able to access non-corporate email in outlook webmail.

If you have any solutions that would be great! Thank you!

[#2]

Define "corporate email". What are you trying to achieve?

[#3]

Corporate email would be like email address removed for privacy reasons. So when a user logs into the Desktop outlook app, they can only login with that email address - not personal or other 3rd party emails.

Essentially I am trying to only allow company email addresses to log into the Outlook app on company assets. The GPO policy that is widely published does this, however it then blocks shared mailboxes which are widely used across my company. I am looking for a solution that does what the GPO policy does but still allows for shared mailboxes.