If you forget your password, Moodle can display a page that enables you to retrieve it. If you enter your username or email address, Moodle will send an email with your login information:

When Moodle sends this email, it confirms the sending but does not display the email address to which the message was sent:

The email address is hidden to protect the user's privacy. Many countries have laws that forbid the disclosure of personal information. If someone could guess the usernames (which is often the case in large institutions), they could enter them into the lost password page and harvest email addresses for abuse.