[#29417] sendMail automatically adds sender as replyTo (Joomla! 2.5.x)

Patch for Joomla 2.5.X

Tracker:
http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=29417

Already sent to Platform: 
joomla/joomla-platform#1564