I like that this service allows me to send mass e-mails without having to deal directly or manually manage any of my campaigns, etc., which saves time -- it also makes sure they're reaching all recipients properly! It's very easy for people who are not tech savvy (like myself)to use as well; no complicated software needed at first glance/signup process only requires your address information so there really isn't much else you need to do before getting started sending out messages. Nothing specifically - everything seems fine from what we've used so far. We had an issue where our message was sent but never delivered due to some sort of DNS error / server issues, though after troubleshooting & contacting support multiple times over about 2 weeks nothing has been resolved yet. This problem stemmed primarily because of how busy other services were during those days when ours wasn’t working correctly, however once again support.