Mail not sent when I set HTML headers

$subject = get_the_title(); 
$sender_name = get_bloginfo('name');
$blog_url = get_bloginfo('url');

$to      = 'myemail@mydomainname.com';
$subject="the subject";
$message="hello";
$headers="MIME-Version: 1.0" . "\r\n";
$headers .= 'Content-type: text/html; charset=iso-8859-1' . "\r\n";
$headers .= 'From: '.$sender_name.' <no-reply@'.$blog_url.'>' . "\r\n";

$headersssssssssssss="From: webmaster@example.com" . "\r\n" .
    'Reply-To: webmaster@example.com' . "\r\n" .
    'Content-type: text/html; charset=iso-8859-1' . "\r\n" .
    'X-Mailer: PHP/' . phpversion();

When I use the $headersssssssssssss variable as a parameter in the mail() function, it works and sends an E-Mail.
But when I use $headers as a parameter, it does not.

Note: I have already tried using wp_mail instead, with the same results.

if( mail($to, $subject, $message, $headersssssssssssss) )
{
    echo '<script>alert("mail sent success!");</script>';
} else {
    echo '<script>alert("mail where not sent");</script>';
} 

exit;

There’s the wp_mail() function in WordPress. The headers have to be added as array without trailing \n\r or similar.

Example

wp_mail(
    'test@example.com',
    'Hello World!',
    'Just saying...',
    array(
        'MIME-Version: 1.0',
        'Content-type: text/html; charset=iso-8859-1',
        sprintf(
            'From: %s <no-reply@%s>',
            get_bloginfo('name'),
            site_url()
        ),
        sprintf( 'X-Mailer: PHP/%s', phpversion() ),
     )
);

To change the content type you could as well use a filter:

<?php
/* Plugin Name: WP Mail Content Type text/html */
function wpse_97789_mail_contenttype( $content_type )
{
    remove_filter( current_filter(), __FUNCTION__ );
    return 'text/html';
}

// Then, whereever you need it, just add the filter before calling the function
// It removes itself after firing once
add_filter( 'wp_mail_content_type', 'wpse_97789_mail_contenttype' );
wp_mail(
    'test@example.com',
    'Hello World!',
    'Just saying...',
    array(
        'MIME-Version: 1.0',
        sprintf(
            'From: %s <no-reply@%s>',
            get_bloginfo('name'),
            site_url()
        ),
        sprintf( 'X-Mailer: PHP/%s', phpversion() ),
    )
);