It may also be preferable in situations when there are long delays in transmission and error rates are variable and high, or if a direct, end-to-end connection is not available.
Point-to-point teleprinter equipment was used to send messages which were stored at the receiving end on punched paper tape at a relay center.
A human operator at the center removed the message tape from the receiving machine, read the addressing information, and then sent it toward its destination on appropriate outbound point-to-point teleprinter link.
A major relay center in the mid 1900s might have dozens of inbound and outbound teleprinters, scores of operators, and thousands of messages in the queues during peak periods.
The UUCP store-and-forward protocols allowed a message (typically e-mail) to move across the collection of computers and eventually reach its destination.