What you need to do is focus on this

$set['dropdown_recipient'] = '0'; /*If you have a dropdown list for potential recipients, put 1. Most will leave to zero... off */
$set['dropdown_name'] = 'send_to'; /*The name of your field for the drop down list... don't use 'recipient' */
$set['dropdown_list'] = $set['recipient'];/*This keeps your email addresses private */
$set['dropdown_email_match'] = '1';/*Autoreply to visitor will be from the email address of person chosen in drop down list... 1=on, zero=off*/
$set['drop_down_default'] = true;/*Will choose the first email in the recipient array (see above) if no dropdown list or checkbox chosen. If set to false, then an error message will appear instead*/


Set the first setting to 1. This tells Ultimate Form Mail that a drop down or list box, or checkbox will be used to pick recipients.

Then put a list box or checkboxes in the html of your form that is named send_to[]. Use numerical values like you see in test4.php

input name="send_to[]" type="checkbox" id="send_to" value="0">admin

The bracket means that multiple checkboxes can be selected.

Then put your email addresses in $set['recipient']

$set['recipient'] = array('you@whatever.com','next@yahoo.com','etc@aol.com');

Note: the number of emails in the list (array) needs to be the same number of options in your form.

Note: 0 is the first value of an array. So in your html, your first option should have a value of 0.