Contact page template - redirect to 'thank you page' not working - forms

Question

I'm trying to submit a form via custom page template but the problem is that it only works with form action="<?php the_permalink() ?>" and I need the form to be submitted and redirected to something like this form action="<?php bloginfo('url')?>/message-sent?id=<?php the_ID() ?>"
Full code:
<?php
$emailError = '';
if(isset($_POST['submitted'])) {
$email = trim($_POST['email']);
//setup self email address
$emailTo = $email;
$subject = "[reminder] Don't forget to download " . get_the_title();
$body = "Name: $name \n\nEmail: $email \n\nComments: $comments";
$headers = 'From: Myemail reminders <no-reply#xyz.com>' . "\r\n";
wp_mail($emailTo, $subject, $body, $headers);
$emailSent = true;
} ?>
<section class="box grid_9 list_posts">
<div class="inner">
<?php if (have_posts()) : while (have_posts()) : the_post(); ?>
<div <?php post_class() ?> id="post-<?php the_ID(); ?>">
<div class="entry-content">
<div class="contact-form clearfix">
<?php if(isset($emailSent) && $emailSent == true) { ?>
<div class="thanks">
<?php _e('Thanks, your email was sent successfully.', 'framework') ?>
</div>
<?php } else { ?>
<?php the_content(); ?>
<?php if(isset($hasError) || isset($captchaError)) { ?>
<p class="error"><?php _e('Sorry, an error occured.', 'framework') ?>
<?php } ?>
<form action="<?php the_permalink()?>" id="contactForm" method="post">
<ul class="contactform">
<li>
<input type="email" name="email" id="email" value="<?php if(isset($_POST['email'])) echo $_POST['email'];?>" class="required requiredField email" required="required" />
</li>
<li class="buttons">
<input type="hidden" name="submitted" id="submitted" value="true" />
<input type="submit" value="Remind Me!"></input>
</li>
</ul></form>
<?php } ?></div>
</div>
</div>
<?php endwhile; else: ?>
<div id="post-0" <?php post_class() ?>>
<h1 class="entry-title"><?php _e('Error 404 - Not Found', 'framework') ?></h1>
</div>
<?php endif; ?></div>
</section>
I got no php errors in log, page is redirected successfully, but no email is sent. When using the_permalink, everything works just fine.

Answer 1

When submitting the form data to a different script, make sure the code for (validating the input and) sending the email is in that very file.
Otherwise, your URL /message-sent might rewrite to a completely different script and the script with the above code isn't involved at all once the submit button gets clicked.
Did that held you? Feel free, to ask, if my wording is incomprehensible or if my description isn't clear to you

Answer 2

Maybe you forgot to put ".php" at the end of your /message-sent?id=xxx file, i.e /message-sent.php?id=xxx?
Another thought: It is always a good idea to filter the user input, because you will receive a lot of spam, put some sort of CAPTCHA validation code and sanitize/validate the whole user input text, i.e. every text, which comes from input fields of your form.
For email:
$email = filter_var($_POST['email'], FILTER_VALIDATE_EMAIL);
For name and comments:
$name = filter_var($_POST['name'], FILTER_SANITIZE_STRING);
$comments = filter_var(strip_tags($_POST['comments']), FILTER_SANITIZE_STRING);