See comments...
<?php
session_start();
function urlsafe_b64decode($string) {
$data = str_replace(array('-','_'),array('+','/'),$string);
$mod4 = strlen($data) % 4;
if ($mod4) {
$data .= substr('====', $mod4);
}
return base64_decode($data);
}
if (!$_SESSION['name']){
echo 'no mail for you';
}else{
$semail = $_SESSION['email'];
$remail = $_GET['email'];
//missing closing brace "}"
if (isset($_POST['submit'])) {
$remail = $_POST['email'];
$sendmessage = $_POST['message'];
$subject = $_POST['subject'];
$headers = 'MIME-Version: 1.0' . "\n";
//mismatched quotes and extra semi-colon, should be $headers .= "Content-Type: text/plain";
$headers .= 'Content-Type: test/plain;";
$message = "
This is an automated message from the low reed site, it was sent by: $name:
----------------- Message is below -----------------
$sendmessage
----------------- Message is above -----------------
Regards,
Admin at low reeds
";
// now send the email
mail($remail, $subject, $message, $headers, "$semail");
}
?>
<form method=post action="">
<input type="hidden" name="email" value="<?php echo urlsafe_b64decode($remail); ?>">
<table>
<tr>
<td>Your e-mail:</td><td><?php echo $semail; ?></td>
</tr>
<tr>
<td>Recipent e-mail:</td><td><?php echo $remail; ?></td>
</tr>
<tr>
<td>Subject</td><td><input type="text" name="subject"></td>
</tr>
<tr>
<td>Message</td><td></td>
</tr>
<tr>
<td></td><td><textarea name=message rows=25 cols=30></textarea></td>
</tr>
<tr>
<td colspan=2><center><input type=submit name=submit value="Mail this person"></td>
</tr>
</table>
</form>
<?php
//Unneeded extra "}"
}
?>
That's all the errors I can see.