404 error when POSTing to custom php

Hi, I own a tattoo studio and I've created a custom page in the members info area (I'm using 4.2.14). The page is a "artists profile" page for my artists with each of their info and links loading from an XML file. I'm trying to provide a text area where members can send an email to my artists personal emails without ever seeing their addresses. Right now I have a form set up like this:

PHP:

<form action="sendmessage.php" method="post">
          <input type="hidden" name="address" value="<?php echo $art->eml ?>">
          <textarea name="message" rows="4" cols="60" placeholder="Send <?php echo $art->name ?> a message!" required></textarea><br>
          <input type="submit" name="submit" value="Send" height="30px">
          </form>

And a custom "sendmessage.php" in the "members" folder that is in the root folder. It looks like this:

PHP:

<?php
if (isset($_POST['submit'])) {
echo "your message was sent";
}
?>

The form action seems to work but it can't seem to find that file. This will contain my email function. I get a 404 error every time. Maybe I'm not putting it in the right place? I would like the file protected inside the members folder. Of course I'm not set on necessarily doing it this way. Can I post to a script already built into amember?

yes, my members folder is the amember folder renamed during the setup process. I had a feeling my problem had to do with security access. I will try it right away. Thank you.

I tried adding it with the other un-commented lines in the htaccess file in my members folder with no effect. then I modified my path in my form to be more specific (../members/sendmessage.php) and that didn't help either. Getting past this little hurdle is very important to me because the same principles will apply to other sections I have planned for the site.

Well, that did work. I wonder if amember will interfere if I use it to set up protection for that folder? I'll try it and post the results in case anyone else out there is wondering.

Ok. I haven't set protection for that folder yet and I built the function to parse the post and send the email as per the DI/API page in the documentation. It gets through all of it and then has an mail send error (the one located on line 21). Here's the code:

PHP:

<?php
include '../members/bootstrap.php';
if (isset($_POST["submit"])) {
$Artmail = $_POST["eml"];
$Uname = $_POST["uname"];
$Rname = $_POST["realname"];
$Umail = $_POST["umail"];
$message = $_POST["message"];
 
$messagefinal = $Uname."\n".$Rname."\n".$Umail."\n".$message;
$messagefinal = wordwrap($message, 70, "\r\n");
$subject = "Tattoo inquiry from ".$Rname;
 
$mail = Am_Di::getInstance()->mail; // create copy of Zend_Mail object, preconfigured by aMember
$mail->addTo($Artmail);
$mail->setSubject($subject);
$mail->setBodyText($message);
try {
  $mail->send();
} catch (Exception $e) {
  echo "Error sending e-mail: " . $e->getMessage() . "\n";
}
 
echo "your message was sent ".$Uname;
echo $messagefinal;
}
?>

The error I get is:"Error sending e-mail: Unable to send mail."