Which dimension is considered the height of a mail piece?

In the context of measuring a mail piece, the height is traditionally associated with the dimension that is perpendicular to the length. This definition aligns with standard practices in mail design and preparation, where dimensions are often referred to in terms of length, width, and height.

Typically, the length is the longest side of the envelope or package, while the width is the shorter side. The height, therefore, represents the dimension that stands upright when the mail piece is resting on a flat surface, differentiating it from both the length and width. This clarity in dimension helps in categorizing mail for postage calculations and in ensuring that it fits within mailing guidelines set by postal services.

While other options refer to dimensions that could be misconstrued, they do not accurately reflect the standard definition used within the mailing industry. Thus, understanding that the height of a mail piece is defined as the dimension that is perpendicular to the length aids in proper categorization and handling of mail.