Users if mentioned receive emails with answers/comments on questions in a restricted space they don't have permissions to view

Summary

Users if mentioned receive emails with answers/comments on questions in a restricted space they don't have permissions to view

Steps to reproduce

1. Ask a question in a restricted space and mention a user that doesn't have permissions to access this space
2. Add a comment to the question and mention the user
3. Answer the question and mention the user

Expected result

The user should not receive emails with contents that he/she doesn't have permissions to view.

Actual result

The user receives emails of those answers/comments. If he/she clicks on the links sent in the emails, the links are blocked. However, the contents are still available in the emails.