All of our prints are carefully rolled and shipped in durable cardboard tubes.
This is because it is almost impossible to ensure a delivery of a flat print that isn't damaged. Since we do not frame or mount, shipping in thin flat cardboard virtually always results in dents or folding. All commercial poster and photographic printers ship the prints rolled in tubes.
For flat printing, the best option is a local photography store that doesn't have to ship the print to you.
When opening your print, be sure to remove the staples holding the end caps in place before removing the prints, as they can scratch the prints on removal. The staples are necessary to prevent the end caps from becoming dislodged and popping out during the carriers handling of the tubes. It's better to deal with the staples than a tube that arrives empty!