Cod PHP:
$email=strtolower($email);
$email=str_replace('e-mail:', '', $email);
$email=str_replace(',', '.', $email);
$email=str_replace('http://', '', $email);
$email=str_replace('www.', '', $email);
$email=str_replace('/', '', $email);
$email=str_replace('@.', '@', $email);
$email=str_replace('.@', '@', $email);
$email=str_replace('iaaho.com', 'yahoo.com', $email);
$email=str_replace('iahoo.com', 'yahoo.com', $email);
$email=str_replace('iahho.com', 'yahoo.com', $email);
$email=str_replace('yohoo.com', 'yahoo.com', $email);
$email=str_replace('ayhoo.com', 'yahoo.com', $email);
$email=str_replace('ayahoo.com', 'yahoo.com', $email);
$email=str_replace('yahao.com', 'yahoo.com', $email);
$email=str_replace('yhaoo.com', 'yahoo.com', $email);
$email=str_replace('yaahhoo.com', 'yahoo.com', $email);
$email=str_replace('yaahho.com', 'yahoo.com', $email);
$email=str_replace('yahho.com', 'yahoo.com', $email);
$email=str_replace('yhoo.com', 'yahoo.com', $email);
$email=str_replace('yhho.com', 'yahoo.com', $email);
$email=str_replace('yaoo.com', 'yahoo.com', $email);
$email=str_replace('tahoo.com', 'yahoo.com', $email);
$email=str_replace('uahoo.com', 'yahoo.com', $email);
$email=str_replace('yahoo.om', 'yahoo.com', $email);
$email=str_replace('yaho.ro', 'yahoo.com', $email);
$email=str_replace('yahoo.ro', 'yahoo.com', $email);
$email=str_replace('yaho.com', 'yahoo.com', $email);
$email=str_replace('yahoo.com', 'yahoo.com', $email);
$email=str_replace('yahoo.comau', 'yahoo.com.au', $email);
$email=str_replace('gmeil.com', 'gmail.com', $email);
$email=str_replace('gmaii.com', 'gmail.com', $email);
$email=str_replace('gmai.om', 'gmail.com', $email);
$email=str_replace('gmail.om', 'gmail.com', $email);
$email=str_replace('gmai.com', 'gmail.com', $email);
$email=str_replace('hotmai.com', 'hotmail.com', $email);
$email=str_replace('hotmail.om', 'hotmail.com', $email);
$email=str_replace('hotamil.com', 'hotmail.com', $email);
$email=str_replace('hotmaii.com', 'hotmail.com', $email);
$email=str_replace('.com...', '.com', $email);
$email=str_replace('.com..', '.com', $email);
$email=str_replace('.com.', '.com', $email);
$email=str_replace('.ro...', '.ro', $email);
$email=str_replace('.ro..', '.ro', $email);
$email=str_replace('.ro.', '.ro', $email);
Probabil ca nu e perfect, dar acopera multe din cazuri.