Effective October 7, 2013, the Postal Service™ will revise Mailing Standards of the United States Postal Service, International Mail Manual (IMM®) to add part 116, which will list Postal Service trademarks that appear throughout the IMM.
Listing the marks in this part will negate the need to use the registered symbol (®) or the trademark symbol (™) throughout the IMM.
We will incorporate this revision into the next update of the online IMM, which is available via Postal Explorer® at http://pe.usps.com.
— Product Classification, Pricing, 9-5-13