note 53514 added to function.header

what is the meaning of thiss error and how to fix it Warning: Cannot modify header information - headers already sent by (output started at /webcorp1/www/corpusers/i/2/i2eye.in/sendemail.php:8) in /webcorp1/www/corpusers/i/2/i2eye.in/sendemail.php on line 57 ---- Manual Page -- http://www.php.net/manual/en/function.header.php Edit -- http://master.php.net/manage/user-notes.php?action=edit+53514 Delete: added to the manual -- http://master.php.net/manage/user-notes.php?action=delete+53514&report=yes&reason=added+to+the+manual Delete: bad code -- http://master.php.net/manage/user-notes.php?action=delete+53514&report=yes&reason=bad+code Delete: spam -- http://master.php.net/manage/user-notes.php?action=delete+53514&report=yes&reason=spam Delete: useless -- http://master.php.net/manage/user-notes.php?action=delete+53514&report=yes&reason=useless Delete: other reasons -- http://master.php.net/manage/user-notes.php?action=delete+53514&report=yes Reject -- http://master.php.net/manage/user-notes.php?action=reject+53514&report=yes Search -- http://master.php.net/manage/user-notes.php