Special Delivery is a postal service for urgent postal packets. Its meaning varies among postal services and is different and separate from Express mail delivery service offered by many postal administrations. Essentially it means that a postal packet is delivered from a post office to the addressee immediately once it arrives at the post office responsible for delivering it, rather than waiting for the next regular delivery to the addressee.
The United States Postal Service offered special delivery from 1885 to 1997 whereby the letter would be dispatched more immediately and directly from the receiving post office to the recipient rather than being put in mail for distribution on the regular delivery route.