What is the maximum height for letters sent via Express Mail?

The maximum height for letters sent via Express Mail is indeed 6 1/8 inches. This specific measurement aligns with the standards set by USPS for what qualifies as a letter in the Express Mail category. Understanding the dimensional limits is crucial for proper mailing, as items not conforming to these specifications may result in delays or the need for alternative mailing options.

Letters that exceed this height or any of the other dimensional limitations can’t be classified as Express Mail letters but might instead need to be sent as a different type of mail service, such as a package or flat. This standard ensures that all items are processed efficiently through the USPS system and that they fit within the automated sorting equipment in use at post offices. Familiarity with these standards helps ensure compliance with postal regulations and can also aid customers in making informed choices about their mailing needs.