Since Moodle 4 (we're now using 4.2), we've noticed that the Email visibility option under "User default preferences" is not honoring our Admin setting.
For security purposes, we need the setting to be: "Hide my email address from non-privileged users".
Despite setting it to the above, we always have to reset it when setting up a new user's profile. For some reason, it always reverts back to the default of: "Allow only other course students to see my email address".