I like that it's easy for me (and my clients) when sending out emails with links or attachments because of how simple they are! Also love their customer support team - very responsive & helpful!! There isn't much i dislike about this program at all but maybe just wish there was an option where you could see what your customers clicked vs opened in order not have them double up clicking so many times haha :) Great tool if used correctly. We use ultra mail 24 mostly during our events/marketing time frame which helps us keep track better than other programs we've tried before hand such as MailChimp etc..