How to enable/disable 'Email this Page to a Friend' in vBulletin?
The “Email this Page to a Friend” functionality can be enabled/disabled per user group.
To modify the option, go to your vBulletin admin panel > Usergroups > Usergroup Manager > Edit Usergroup > Can Use Email to Friend. Pick whether you want to enable or disable the feature for the chosen user group and save the new settings.