Here's an example with some notes.
$('.myform').submit(function () {
getEmailAddresses();
return false;
}
function getEmailAddresses () {
// a place to hold them
var emails = new Array();
// what will be after 'mailto'
var emailsString = "";
// get 'em
$('.checkedsupplier').each(function () {
// get the hidden email input value
var email = $(this).find('.supplieremail').val();
// check, just in case;
if (email) {
// push the value into our array
emails.push(email);
}
});
//put them all together into a string, split by a semi-colon
emailsString = emails.join(';');
// finally, stuff our mail to link.
// Not sure what you're plan is here but 'emailsString' has all of the values you eed.
$('.mailtolink').attr('href', 'mailto:'+emailsString);
}