Somewhere in your page you need a form similar to this:
<form action="handle_form.php" method="POST">
<select name="email">
<option value="email1@example.com">USA</option>
<option value="email2@example.com">Canada</option>
<option value="email3@example.com">Venezuela</option>
<input type="submit" name="submit" value="Submit">
<input type="hidden" name="submitted" value="TRUE">
</select>
</form>
Then, you will need to "handle" the form. This can be done in the same page or another one. Notice that in this case , I am going to pass the data to "handle_form.php"
The "handle_form.php" will look something like this:
<?php
if (isset($_POST['submitted']) ){ // if the form has been submitted
echo "You will be emailing $_POST['email'] ";
}else {
echo "what are you doing here?";
}
?>
Obviously you won't be outputting the e-mail like that. However, this shows you how to get access to the value from the drop-down menu.
Hope that helps.
p.s. - I didn't double check all of this so test it out and let me know if it works. If not the let me know and i'll help you out.