Bevestiging dat formulier verzonden is wordt niet geplaatst (Opgelost)

<script language="Javascript">
function validate(){
var allok = true;
 
  if(Formulier.Email_adres__8.value.indexOf("@") == -1){
    alert('Vul hier een correct e-mail adres in alstublieft');
    return false;
  }
document.Formulier.Submit.disabled="disabled";
return true;
}
</script>
<form name="Formulier" method="Post" action="Verzonden.php" onSubmit="return validate();">

<table width="100%" border="0" cellpadding="5" cellspacing="0">

<tr>
<td>Aanhef</td>
<td><input type="checkbox" name="De_heer__2">De heer<br>
<input type="checkbox" name="Mevrouw__2">Mevrouw<br></td>
</tr>

<tr>
<td>Naam</td>
<td><input type="text" required name="Naam" size="40" x-moz-errormessage="Gelieve dit veld correct in te vullen"></td>
</tr>

<tr>
<td>Telefoonnummer(s)</td>
<td><input type="tel" required name="Telefoonnummers" size="40" x-moz-errormessage="Gelieve dit veld correct in te vullen"></td>
</tr>

<tr>
<td>Email adres</td>
<td><input type="email" required name="Email_adres" size="40" x-moz-errormessage="Gelieve dit veld correct in te vullen"></td>
</tr>

<tr>
<td colspan=2 valign=top>Uw bericht<br><textarea name="Uw_bericht" required cols="80" rows="10" x-moz-errormessage="Gelieve dit veld correct in te vullen"></textarea></td>
</tr>

<tr>
<td colspan=2><input type="submit" name="Submit" value="Uw bericht verzenden"></td>
</tr>

</table>
</form>

<script language="Javascript">
function validate(){
var allok = true;
 
  if(Formulier.Email_adres__8.value.indexOf("@") == -1){
    alert('Vul hier een correct e-mail adres in alstublieft');
    return false;
  }
document.Formulier.Submit.disabled="disabled";
return true;
}
</script>
<form name="Formulier" method="Post" action="Verzonden.php" onSubmit="return validate();">
 
<table width="100%" border="0" cellpadding="5" cellspacing="0">
 
<tr>
<td>Aanhef</td>
<td><input type="checkbox" name="De_heer__2">De heer<br>
<input type="checkbox" name="Mevrouw__2">Mevrouw<br></td>
</tr>
 
<tr>
<td>Naam</td>
<td><input type="text" required name="Naam" size="40" x-moz-errormessage="Gelieve dit veld correct in te vullen"></td>
</tr>
 
<tr>
<td>Telefoonnummer(s)</td>
<td><input type="tel" required name="Telefoonnummers" size="40" x-moz-errormessage="Gelieve dit veld correct in te vullen"></td>
</tr>
 
<tr>
<td>Email adres</td>
<td><input type="email" required name="Email_adres" size="40" x-moz-errormessage="Gelieve dit veld correct in te vullen"></td>
</tr>
 
<tr>
<td colspan=2 valign=top>Uw bericht<br><textarea name="Uw_bericht" required cols="80" rows="10" x-moz-errormessage="Gelieve dit veld correct in te vullen"></textarea></td>
</tr>
 
<tr>
<td colspan=2><input type="submit" name="Submit" value="Uw bericht verzenden"></td>
</tr>
 
</table>
</form>

<?php
$email = "info@mijnwebsite.nl";
$message = "Bericht verzonden vanaf mijn website";
$message .= "Aanhef: ".$_REQUEST[Aanhef__2]."\n\n";
$message .= "De heer: ".$_REQUEST[De_heer__2]."\n\n";
$message .= "Mevrouw: ".$_REQUEST[Mevrouw__2]."\n\n";
$message .= "Naam: ".$_REQUEST["Naam"]."\n\n";
$message .= "Telefoonnummer(s): ".$_REQUEST["Telefoonnummers"]."\n\n";
$message .= "Email adres: ".$_REQUEST["Email_adres"]."\n\n";
$message .= "Uw bericht: ".$_REQUEST["Uw_bericht"]."\n\n";
mail( $email, "Bericht verzonden vanaf mijn website", $message, "From: $email
 X-Priority: 1 (Highest)" );
header("Location: http://www.naamvanmijnwebsite.nl/Contact.html");
?>

<?php
$email = "info@mijnwebsite.nl";
$message = "Bericht verzonden vanaf mijn website";
$message .= "Aanhef: ".$_REQUEST[Aanhef__2]."\n\n";
$message .= "De heer: ".$_REQUEST[De_heer__2]."\n\n";
$message .= "Mevrouw: ".$_REQUEST[Mevrouw__2]."\n\n";
$message .= "Naam: ".$_REQUEST["Naam"]."\n\n";
$message .= "Telefoonnummer(s): ".$_REQUEST["Telefoonnummers"]."\n\n";
$message .= "Email adres: ".$_REQUEST["Email_adres"]."\n\n";
$message .= "Uw bericht: ".$_REQUEST["Uw_bericht"]."\n\n";
mail( $email, "Bericht verzonden vanaf mijn website", $message, "From: $email
 X-Priority: 1 (Highest)" );
header("Location: http://www.naamvanmijnwebsite.nl/Contact.html");
?>