General Delivery is a mail service for those without a permanent address, often used as a temporary mailing address. General Delivery is intended to be used for Post Office locations without city carrier delivery service, non-city delivery offices for those who prefer not to use Post Office Box service and for whom use of Post Office box, Caller Service, or delivery by letter carrier, would be an unreasonable inconvenience, a participating Post Office to serve transients (people who travel extensively) and those without a permanent address, and anyone who wants Post Office box service when Post Office boxes are unavailable. Each piece of General Delivery mail is held for no more than 30 days, unless the sender requests a shorter period. General Delivery mail may be held for longer periods if requested by sender or addressee and approved by postmaster. Mail without a specific address or instructions from the sender is held for: 10 days if for General Delivery at an office with letter-carrier service; 15 days if for General Delivery at an office without letter-carrier service.