Home › CFR › Title 39 › Part 31039 CFR Part 310 — Enforcement of the Private Express Statutes§ 310.1— Definitions.§ 310.2— Unlawful carriage of letters.§ 310.3— Exceptions.§ 310.4— Responsibility of carriers.§ 310.5— Payment of postage on violation.§ 310.6— Advisory opinions.§ 310.7— Amendment of regulations.