Not mailable; that cannot (legally) be sent by mail.(adjective)
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Use "nonmailable" in a sentence
"WHAT THIS MEANS TO YOU: By making all cigarettes and smokeless tobacco products nonmailable, the Senate is ensuring you will no longer be able to purchase these products by mail-order, telephone order, and/or the Internet because the United States Postal Service will be prohibited from delivering your orders to you."
"Prevent All Cigarette Trafficking Act of 2009 ( "PACT Act") (S. 1147) which contains, among other bad ideas, a provision to make ALL cigarettes and smokeless tobacco products nonmailable."