The most frequently used of our Postal Services applies to a sealed letter post items. First Class mail is designed for letters, business documents and floppy disks that contain data, and hand or type written messages. Anything that has the character of personal correspondence is considered first class matterandmust be sent at the first class rate. First class mail may not be opened for postal inspection by the Post Office, and is the fastest class of mail, except for Express Mail.
