Tell a Friend FROM Email should be set to primary participant email in multi-participant scenario

When registering as an ANONYMOUS user.... If you've enabled Multiple Participant Registration for an event, as well as Tell a Friend, then the Tell a Friend screen picks up the last participant' email as the FROM email address (and this is read-only). The FROM email address should be the primary participant.

http://forum.civicrm.org/index.php/topic,4470.0/topicseen.html

(This bug does not happen if you are registering as a logged in user).