Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Hello
Do you mean only when you go to www.outlook.com on the web?
If so, it sounds like you are using a third party email address, such as Gmail or Yahoo, as the sign-in username/alias for your Microsoft account. Is that correct?
When your Microsoft account uses a non-Microsoft email address, it does not have its own email functionality. The actual sending and receiving of emails still happens through your third party email provider. The third party email address servies as username only. Nothing more,
www.outlook.com is the web-based email for outlook.com and hotmail.com addresses only. Hence, when you go there, apparently it cannot perform email functions for your third party email, so it shows a native outlook.com placeholder email.