The "delivers deliver" text loop is a known text-engine bug in the North American GameCube version. It occurs when the delivery-notification queue gets stuck—often after receiving multiple letters/packages rapidly or due to a corrupted mail flag in the save.
If the glitch persists after steps 1–4, the save's mail structure is likely corrupted. Step 5 (new memory card copy) is the last safe attempt before accepting the annoyance or restarting.