the only modification that needs to happen to the form is adding "[]" to the name of the element to create the array.
In universal email, you need to modify the email message.
to get the value of the form element into the email, it will use the following code:
<?php echo((isset($_POST["Services"]))?$_POST["Services"]:"") ?>
this code in the email message needs to be modified to convert the array to a string using implode function:
<?php echo((isset($_POST["Services"]))?implode(", ", $_POST["Services"]):"") ?>