An event was deleted from the calendar AND:
You created a notification request so that you would be sent an Email about any events added to the calendar AND the system wide setting "Re-Process Notification Requests on Event Change" is set to "Yes".
OR
Another user created a notification request and added you as a CC recipient for the notification request he created. The name and Email address of the user who created the notification request will be shown in the Additional Information section of the Email.
OR
You have created a reminder for the event, and the option to "Notify on Change" was checked.
OR
Another user created a reminder for the event with the option to "Notify on Change" checked, and they added you as a CC for the reminder.
Disabling Reminder Generated Messages:
If you created the reminder, delete it by going to the calendar, clicking on the event to view the event details, and then click on the Alarm Icon.
If another user created the reminder, contact them and ask to be removed from the reminder. The contact information for the person who created the reminder will be displayed in the Additional Information section.
Disabling Notification Request Generated Messages:
Follow the link in the message to edit or delete the notification request.
If another user created the notification request and added you as a CC, ask them to remove you.