Send mail form not working - php

Question

$location ="/contact.php";
if(isset($_POST[$form_names['email']], $_POST[$form_names['subject']], $_POST[$form_names['mess']])){
if($csrf->check_valid('post')){
$email = trim(htmlspecialchars($_POST[$form_names['email']]));
$subject = trim(htmlspecialchars($_POST[$form_names['subject']]));
$mess = trim(htmlspecialchars($_POST[$form_names['mess']]));
if ($email == '' && $subject == '' && $mess == ''){
// $message = "Success";
$headers = "From: {$email}\r\n".
"Content-Type: text/html; charset=ISO-8859-1\r\n";
$current_ip = $_SERVER['REMOTE_ADDR'];
$html_message = nl2br($mess);
$sub = "CONTACT FORM: ".$subject;
//send email
$to = SITE_EMAIL;
$the_mess = "IP: ".$current_ip." <br />
FROM: ".$email."<br />
MESSAGE: <p />"."$html_message";
mail($to, $sub, $the_mess, $headers);
$message = "<div class='alert alert-success'><button type='button' class='close' data-dismiss='alert'>x</button>Thank you, your message has been sent successfully.</div>";
} else {
$message = "<div class='alert alert-danger'><button type='button' class='close' data-dismiss='alert'>x</button>Please complete all required fields.</div>";
}
}
And form:
<form action="<?php echo $location; ?>" method="post" class="form-horizontal" enctype="multipart/form-data">
<label for="subject">Choose Department:</label><br>
<select id="subject" name="<?php echo $form_names['subject']; ?>" class="form-control">
<option value="activation">Account activation</option>
<option value="suspension">Account suspension</option>
<option value="auctions">Auctions</option>
<option value="complaint">Complaints</option>
<option value="others">Others</option>
</select>
<br />
<label for="email">Email Address</label>
<input type="text" class="form-control" name="<?php echo $form_names['email']; ?>" autocomplete="off" value="<?php echo htmlspecialchars($email); ?>" placeholder="Enter your Email Address">
<br />
<label for="email">Please describe your problem</label>
<textarea type="text" class="form-control" style="height:111px;" name="<?php echo $form_names['mess']; ?>" placeholder="Your Message" required="required"><?php echo htmlspecialchars($mess); ?></textarea>
<input class="btn btn-danger" type="submit" name="submit" value="Send Message" />
</form>
When I submit the form, it outputs the second $message:
Please complete all required fields.
I cannot find the issue here. I tried print_r(error_get_last()); and it does not show any errors. Any help would be much appreciated. Thank you very much!

Answer 1

Your condition is if ($email == '' && $subject == '' && $mess == ''){, this means that the mail is sent only if all the fields are empty.
I'm assuming the correct condition should be like if ($email != '' && $subject != '' && $mess != ''){