Form Mailto With List Of Names Using Checkboxes?

I found a script on this forum that does almost what I want from this thread: [URL]. Instead of a dropdown, I'd like to have a list of names using check boxes, so that you have the option to send an email to one or all of the people. When you choose your selections and click submit, an outlook email will pop up with your selections in the to: field.

Here's the solution using a drop down, this works (and works well), but doesn't quite do what I need :
<form name="Contact_Us" id="contact" method="post" enctype="text/plain" onsubmit = "getEml()">
<fieldset id="selection">
Who would you would like to email:
<select name = "sel">
<option value="email1@email.com" >email 1</option>
<option value="email2@email.com" >email 2</option>
<option value="email3@email.com" >email 3</option>
</select>
<input type = "submit" value = "Submit the form">
</form>

<script type = "text/javascript">
function getEml() {
var emailaddress = document.Contact_Us.sel.value;
window.location = "mailto:" + emailaddress;
}
</script>

Is there a way to use checkboxes but to do the same thing?
<INPUT TYPE=CHECKBOX NAME="name1@email.com">name 1<BR>
<INPUT TYPE=CHECKBOX NAME="name2@email.com">name 2<BR>
<INPUT TYPE=CHECKBOX NAME="name3@email.com">name 3<BR>