Create your message using HTML but do not use double quotes in your message.
Use example as follows:
$header = "From: Site Title <$users_email>\n";
$header .= "MIME-Version: 1.0\n";
$header .= "Content-Type: text/html; charset=iso-8859-1\n";
$header .= "X-Priority: 1\n";
$header .= "X-Mailer: PHP / ".phpversion()."\n";
$message = "<html>\n";
$message .= "<body>\n";
$message .= "<table border=0 cellspacing=0 cellpadding=0>\n";
$message .= "<tr>\n";
$message .= "<td>Just text in the table cell</td>\n";
$message .= "</tr>\n";
$message .= "</table>\n";
$message .= "</body>\n";
$message .= "</html>\n";
$sendto = $destination_email;
$subject = "Subject of email";
mail($sendto,$subject,$message,$header);