What is "forwardings"

Usage examples of "forwardings".

Several times, when Ginny and I were especially busy, we have let what appeared to be fan mail pile up unread-and this is a mistake as again and again there has turned out to be one or more actual business letters buried in the fan mail simply because the external appearance (one or two forwardings, with nothing in the return address to tip me) led me to assume that it was fan mail.