Actually mom use to send me nanna bread all the time in the mail-no problems
From LA up here is prolly at least a couple or three days as she sent parcel post (a letter takes 3 days).
Mom used all kinds of weird boxes - empty ceral and crakcers were often her favorite, and the nanna bread was just in foil, bagged, then 3 mini loaves fit into a ceral box and into the big box. Sue used the same for cookies wrapped in tissue paper then in the boxes or tins. Got this every year for the holidays.