<?
setlocale(LC_ALL, 'de_DE.UTF-8');
$_POST['Betreff']='ÄÖÜß Test 1€';
$_POST['Absender']='"ÄÖÜß Test" <a@local>'; 
$_POST['Text']='
Aha!

Soso!

ÄÖÜß

';
mail('email@local', 
	"Subject: " . mb_encode_mimeheader($_POST['Betreff'], 'utf-8', 'Q'), 
	$_POST['Text'], 
    'From: ' . mb_encode_mimeheader($_POST['Absender'],  'utf-8', 'Q') . "\n" 
      . 'Content-Type: text/plain; charset="utf-8"' . "\n" 
      . 'Content-Transfer-Encoding: 8bit' 
	);
?>