What the hell is a courier reminder?

Warm reminder means friendly reminder, which is explained with a gentle attitude. Failure to deliver correctly means failure to deliver successfully. The main reason may be the shipper, who found that there was something wrong with the courier and asked for a return. It is also possible that the courier company can't deliver the goods because it doesn't know the courier information, or it may choose to return the goods. If you really encounter this situation, you can contact the sender first, or you can find the courier company to find out the reason, and then you can deal with it in time.