1 Letter-size Basics
1-1 Types of Letter-size Mail
1-2 Physical Standards for Letters
1-2.1 Dimensional Standards for Letters
1-2.2 Length and Height
1-2.3 Aspect Ratio
1-3 Address Placement for Letters
1-3.1 Nonmailable Placement of the Delivery Address
1-3.2 Proper Delivery Address Placement
1-3.3 Proper Return Delivery Address Placement
