test PHP mail() - php

Question

I have a mail submission script that is working exactly as expected on both a dev environment and live with one exception. I am getting conflicting results from the mail() test conditional on the live environment vs the dev environment.
On my dev environment it redirects to $ThanksURL on success. On the live server even through the mail is successfully the script proceeds to the else statement and redirects back to the form page.
This has been driving me crazy so any ideas as to why would be most welcome.
Snippet of the issue:
$ok = #mail($to, $subject, $message, $headers, $returnpath);
if($ok){ header("Location: $ThanksURL");
exit;
}else{ $_SESSION['error'] .= " There has been a problems submitting your details. <br />";
header("Location: $form");
exit;
}// end if ok
Script in full:
<?php
session_start();
$form = 'index.php';
$_SESSION['error'] = "The following errors have occured: ";
if(isset($_POST['submitted'])) {
// email fields: to, from, subject, and so on
// Here
$from = "Form Feedback <******#gmail.com>";
$to = "******#gmail.com";
$subject = "Competition";
$ThanksURL = "thankyou.html";
$headers = "From: $from";
$returnpath = "-f" . $from;
$attachment = 0; // is there an attachement
//form fields
$emailAddress = stripslashes($_POST['email']);
$phone = stripslashes($_POST['phone']);
$comments = stripslashes($_POST['comments']);
//basic message info
$message = "Info submitted:\n\nEmail address: " .$emailAddress ."\n\nPhone number: " .$phone."\n\nComments:\n ".$comments. "\n\n";
if($_FILES['attachment']['error'] == 4) {
$message .="No attachement included";
}else{
// test file type and size for submission
$allowedExts = array("doc", "docx", "pdf", "txt");
$extension = end(explode(".", $_FILES['attachment']["name"]));
if ((($_FILES['attachment']["type"] == "application/msword")
|| ($_FILES['attachment']["type"] == "application/vnd.openxmlformats-officedocument.wordprocessingml.document")//docx mime
|| ($_FILES['attachment']["type"] == "application/pdf")
|| ($_FILES['attachment']["type"] == "application/plain")
|| ($_FILES['attachment']["type"] == "text/plain"))
&& ($_FILES['attachment']["size"] < 2097152 )
&& in_array($extension, $allowedExts)){
// boundary
$semi_rand = md5(time());
$mime_boundary = "==Multipart_Boundary_x{$semi_rand}x";
// headers for attachment
$headers .= "\nMIME-Version: 1.0\n" . "Content-Type: multipart/mixed;\n" . " boundary=\"{$mime_boundary}\"";
// multipart boundary
$message = "--{$mime_boundary}\n" . "Content-Type: text/plain; charset=\"iso-8859-1\"\n"."Content-Transfer-Encoding: 7bit\n\n" . $message . "\n\n";
// prepare the files uplaod
$message .= "--{$mime_boundary}\n";
$fp = #fopen($_FILES['attachment']['tmp_name'],"rb");
$data = #fread($fp,filesize($_FILES['attachment']['tmp_name']));
#fclose($fp);
$data = chunk_split(base64_encode($data));
$message .= "Content-Type: application/octet-stream; name=\"".$_FILES['attachment']['name']."\"\n"."Content-Description: ".$_FILES['attachment']['name']."\n" ."Content-Disposition: attachment;\n" . " filename=\"".$_FILES['attachment']['name']."\";size=".$_FILES['attachment']['size'].";\n"."Content-Transfer-Encoding: base64\n\n" . $data . "\n\n";
$message .= "--{$mime_boundary}--";
}else{
$_SESSION['error'] .= "Error: " . $_FILES["attachment"]["name"] . " is not a doc, docx, pdf or txt file or is larger than 2mb. Please resubmit <br />";
header("Location: $form");
exit;
}
}//file conditional
//prepare mail
$ok = #mail($to, $subject, $message, $headers, $returnpath);
if($ok){
header("Location: $ThanksURL");
exit;
}else{
$_SESSION['error'] .= " There has been a problems submitting your details. <br />";
header("Location: $form");
exit;
}// end if ok
}// end sub
?>

Answer 1

Sorry to say this, but php mail can return something else on success than true or false, like mentioned in the php manual comment. Also, it is known to return false on success on some situations, too.
PHP mail() is a kludgy function from many different angles, and personally I would advise against using it in production systems. There are quite a few alternatives, such as swift mailer, PHP mailer, Zend_Mail etc.
However, if you want to use it, you should definitely log the actions and in this case, return values, and not have # to hide your return values.
As a summary, in this case mail() returned an empty string, and not true or false.