带变量的php-html电子邮件

Question

Hallo I've got a problem with sending html E-mails with a dyanamic Link via PHP. That is my PHP Code:

$empfaenger = $_POST['email'];
$test = sha1($_POST['email']);
$betreff = "Test Mail";
$from = "From: Peter <[e-mail]>
";
$from .= "Reply-To: [e-mail]
";
$from .= "Content-Type: text/html
";
$text = "Please click <p><a href='http://defaultpage/default.php?res=".$test."'>here</a></p>.";
mail($empfaenger, $betreff, $text, $from);

In the mail Log all looks normal like the mail is sended, but I didn't receive one. In PHP error Log also nothing. If I set $test to a specified string it's working as expected, but not with the dyanamic variable $test. I hope that someone can help me becuse I can't get rid of this problem.

</div>