If you want Mail to automatically add events for you, choose Mail > Preferences, click General, then select Add invitations to Calendar automatically.
For an > System Preferences, click Siri, click Siri Suggestions & Privacy, then deselect the Mail checkbox. If you change your mind later, select the checkbox.
Open Siri preferences for me
You can add events and information to Calendar and Contacts yourself. Move the pointer over a date, time, phone number, email address, or street address until an outline appears, then click the arrow to take an action.