Hello Reader's if you want to send the checkbox in post for this you have to pass the form name as an array and afterwards you can access all checked boxes using the var itself which would then be an array. Lets consider the example below:-

<form method='post' id='userform' action='thisform.php'> <tr>
    <td>Trouble Type</td>
    <td>
    <input type='checkbox' name='checkboxvar[]' value='Option One'>1<br>
    <input type='checkbox' name='checkboxvar[]' value='Option Two'>2<br>
    <input type='checkbox' name='checkboxvar[]' value='Option Three'>3
    </td> </tr> </table> <input type='submit' class='buttons'> </form>

<?php 
if (isset($_POST['checkboxvar'])) 
{
    print_r($_POST['checkboxvar']); 
}
?>

To echo checked options into your email you would then do this:

echo implode(',', $_POST['checkboxvar']); // change the comma to whatever separator you want