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U.S. Code of Federal Regulations
Regulations most recently checked for updates: Oct 06, 2025
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Title 39
Chapter I
Part 121 - PART 121—SERVICE STANDARDS FOR MARKET-DOMINANT MAIL PRODUCTS
§ 121.0 - Market-dominant product service standards.
§ 121.1 - First-Class Mail.
§ 121.2 - Periodicals.
§ 121.3 - USPS Marketing Mail.
§ 121.4 - Package Services.
Appendix Appendix A - Appendix A to Part 121—Tables Depicting Service Standard Day Ranges
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