The “Delivery Unconfirmed” status indicates that your message was not received, or the recipient device did not send a delivery receipt. This typically happens when the recipient is not in range or is at the very edge. It’s also possible the message reached your recipient but conditions changed before a delivery receipt could make it back to you — especially if you’re meshing and/or moving around a lot.
You can try sending the message again by clicking on “Delivery Unconfirmed”. Changing locations may result in a better chance for success. For example, if you're in a ravine, behind a big boulder, or blocked by a large building, try elevating the device (or standing on a higher surface) or getting around the obstacle. Also, remember to wear your goTenna Mesh as high as possible.