31 CFR § 594.509 - Transactions related to mail authorized.

All transactions by U.S. persons, including payment and transfers to common carriers, incident to the receipt or transmission of mail between a U.S. person and a person whose property or interests in property are blocked pursuant to § 594.201(a) are authorized, provided the mail is limited to personal communications not involving a transfer of anything of value and not exceeding 12 ounces in weight.