Why do you guys even think it would be possible to use HTC Messaging Client to send MMS with Sprint? IMO...if it were possible to do, I'm pretty sure HTC would have included HTC Messaging Client in the Sprint Sense 2.5.2011 ROM (only up to 2016 packages now, so it's not like it's a super old version). No one has found the correct setting for Sprint since HTC Messaging Client was first included in a ROM, which was many months ago. I'd love to be proved wrong though
.