Tagging a person in Notes of CRM - Permission Denied to view

Tagging a person in Notes of CRM - Permission Denied to view

A few days ago we started having an error. 
When a person is tagged in the notes section of the CRM an email is generated. The person receiving the email (who was tagged) is unable to click the VIEW MESSAGE and actually view the message. They get a Permission Denied Notification. 
What changed, and how is this fixed? 
Thank you, 
Kim

See screen Shot