The term of mail service refers to the postal system, which is a system of delivering physical mail from one person to another. It is a centuries-old system that has been used for communication and commerce since ancient times. The postal system is managed by the government and is responsible for delivering letters, packages, and other items to their intended recipients. Postal workers are responsible for sorting, delivering, and collecting mail from post offices and other locations. The postal system is an important part of modern life, as it allows people to communicate with each other quickly and easily.