USPS only allows shipments of handguns between dealers or manufacturers or individual to a dealer.
"
individual to a dealer."
Not correct at all as a matter of federal law. USPS only allows mailing handguns from one manufacturer or dealer to another manufacturer or dealer. There are some other extremely limited exceptions for military, LE, etc., but they are not relevant to this thread.
A non-manufacturer or dealer (who does not fit within one of the other extremely limited exceptions to the statute) who mails a handgun is committing a federal felony.
The law:
Section 1715. Firearms as nonmailable; regulations
Pistols, revolvers, and other firearms capable of being concealed on the person are nonmailable and shall not be deposited in or carried by the mail or delivered by any officer or employee of the Postal Service. Such articles may be conveyed in the mail, under such regulations as the Postal Service shall prescribe, for use in connection with their official duty, to officers of the Army, Navy, Air Force, Coast Guard, Marine Corps, or Organized Reserve Corps; to officers of the National Guard or militia of a state, territory, commonwealth, possession, or district; to officers of the United States or of a state, territory, or district whose official duty is to serve warrants of arrest or commitments; to employees of the Postal Service; to officers and employees of enforcement agencies of the United States; and to watchmen engaged in guarding the property of the United States, a state, territory, commonwealth, possession, or district.
Such articles also may be conveyed in the mail to manufacturers of firearms or bona fide dealers therein in customary trade shipments, including such articles for repairs or replacement of parts, from one to the other, under such regulations as the Postal Service shall prescribe. Whoever knowingly deposits for mailing or delivery, or knowingly causes to be delivered by mail according to the direction thereon, or at any place to which it is directed to be delivered by the person to whom it is addressed, any pistol, revolver, or firearm declared nonmailable by this section, shall be fined under this title or imprisoned not more than two years, or both.
18 U.S.C. 1715
Congress gave the USPS authority to promulgate regulations regarding the shipping of handguns between manufacturers and bona fide dealers. The USPS did so with the Domestic Mail Manual.
http://pe.usps.com/text/dmm300/dmm300_landing.htm
The Domestic Mail Manual defines manufacturers and dealers as: "Licensed manufacturer and licensed dealer mean, respectively, a manufacturer of firearms or a bona fide dealer of firearms, duly licensed by the Bureau of Alcohol, Tobacco and Firearms of the Department of the Treasury, under the Gun Control Act of 1968 (Public Law 90-618), 18 USC 921, et seq."
From the Domestic Mail Manual:
601 Mailability
11.1.5 Manufacturers and Dealers
Handguns may also be mailed
between licensed manufacturers of firearms and licensed dealers of firearms in customary trade shipments, or for repairing or replacing parts.
http://pe.usps.com/text/dmm300/601.htm#wp1065404
Here is the language from the Form 1508 a person must sign to mail a handgun:
"The undersigned is a manufacturer of firearms or bona fide dealer therein, and the parcels presented for mailing herewith are customary trade shipments or other articles for repair or replacement of parts. To the best of my knowledge and belief, the addressees are manufacturers of firearms or bona fide dealers therein."