Automatically sets read receipts on any webmail you send. Can still be disabled manually.

webmailreceipts.user.js

// ==UserScript==
// @name         Connexus WebMail Automatic Read Receipt
// @namespace    http://tampermonkey.net/
// @license      GPL3
// @version      0.1
// @description  Automatically sets read receipts on any webmail you send. Can still be disabled manually.
// @author       Zach Mertes
// @match        https://www.connexus.com/webmail*
// @include      https://www.connexus.com/webmail*
// @grant        none
// ==/UserScript==

(function() {
    'use strict';
    var inCompose = false;
    $(document).bind("DOMSubtreeModified", function(evt) {
        var hasReceiptBox = $('#notification').length > 0;
        if (hasReceiptBox && !inCompose) {
            inCompose = true;
            setTimeout(() => {
                if ($('#notification')[0].checked === false) {
                    $('#notification')[0].click();
                }
            },1000);
        } else if (!hasReceiptBox && inCompose) {
            inCompose = false;
        }
    });
})();