I have been trying to get away from Google lately so I am trying to use the Mac Calendar app for my calendar. I want email notifications for my events but Calendar always launches the Mail app even though outlook is my default mail app.
Sorry, that is not possible since Mac calender only works with mac Mail to send the alerts.
However, in Mac mail, you would be using your chosen email provider (same as in Outlook) so the emails would be send using that provider.
The receiver would not know where the email came from.