I should give you more details. I only use POP mail. I do not check it from more than one location. It doesn't matter if I go directly to the web mail or a client, it's the dupe email every time that gets sent to my email provider. My take is that the connection is getting interrupted every single time and it's something server side, as in for whatever reason your server isn't receiving a confirmation of delivery. My opinion is, that if it was recipient side not sending confirmation, then it would certainly be happening with more senders not just you. Again, I have NEVER gotten any dupes from anyone but GoDaddy, and with yours it every time.