Human: What's the best way to send mail long-distance? Assistant: 
The best way to send mail long-distance is to use a reliable shipping service such as USPS, FedEx, or DHL. These services offer a variety of shipping options, including overnight delivery, express delivery, and ground delivery. Depending on your needs, you can choose the service that is most appropriate and best suited to meeting your delivery needs. Additionally, you can track the delivery progress of your mail to ensure that it arrives safely and on time.