Ajax contact form not submitting and "AN ERROR OCCURRED: ERROR" message - ajax

Question

I'm trying to get a contact form to send information(name, email and message) to a personal email, but it keeps returning "AN ERROR OCCURRED: ERROR" and I've hit a wall on what I am doing incorrectly.
It should just submit the form to my personal email, but when trying to select the 'submit' button it gives me the above message and doesn't display anything else.
Here is the html:
<form name="ajax-form" id="ajax-form" action="mail-it.php" method="post">
<div class="eight columns">
<label for="name">
<span class="error" id="err-name">please enter name</span>
</label>
<input name="name" id="name" type="text" placeholder="Your Name: *"/>
</div>
<div class="eight columns">
<label for="email">
<span class="error" id="err-email">please enter e-mail</span>
<span class="error" id="err-emailvld">e-mail is not a valid format</span>
</label>
<input name="email" id="email" type="text" placeholder="E-Mail: *"/>
</div>
<div class="sixteen columns">
<label for="message"></label>
<textarea name="message" id="message" placeholder="What's on your mind"></textarea>
</div>
<div class="ten columns offset-by-six">
<div id="button-con"><button class="button-primary" id="send"><span data-hover="submit">submit</span></button></div>
</div>
<div class="clear"></div>
<div class="error text-align-center" id="err-form">There was a problem validating the form please check!</div>
<div class="error text-align-center" id="err-timedout">The connection to the server timed out!</div>
<div class="error" id="err-state"></div>
</form>
Here is the mail-it.php markup:
<?php
$send_to = "enter#youremail.com";
$send_subject = "ajax form";
$f_name = cleanupentries($_POST["name"]);
$f_email = cleanupentries($_POST["email"]);
$f_message = cleanupentries($_POST["message"]);
$from_ip = $_SERVER['REMOTE_ADDR'];
$from_browser = $_SERVER['HTTP_USER_AGENT'];
function cleanupentries($entry) {
$entry = trim($entry);
$entry = stripslashes($entry);
$entry = htmlspecialchars($entry);
return $entry;
}
$message = "This email was submitted on " . date('m-d-Y') .
"\n\nName: " . $f_name .
"\n\nE-Mail: " . $f_email .
"\n\nMessage: \n" . $f_message .
"\n\n\nTechnical Details:\n" . $from_ip . "\n" . $from_browser;
$send_subject .= " - {$f_name}";
$headers = "From: " . $f_email . "\r\n" .
"Reply-To: " . $f_email . "\r\n" .
"X-Mailer: PHP/" . phpversion();
if (!$f_email) {
echo "no email";
exit;
}else if (!$f_name){
echo "no name";
exit;
}else{
if (filter_var($f_email, FILTER_VALIDATE_EMAIL)) {
mail($send_to, $send_subject, $message, $headers);
echo "true";
}else{
echo "invalid email";
exit;
}
}
?>