Noted by Cal Hahn as earliest reported receipt for a valuable letter is this one which reads:

"Marshall Post Office Dec. 1, 1840
I do hereby Certify that Messrs. Gorham & Brown have this day deposited in this Office to Mail a letter addressed Higginson & Clapp of New York Containing Two hundred dollars in bills of different banks. Chas. D Smith P.M."

This note signed by the postmaster attested to the fact a patron deposited into the mails a letter containing two hundred dollars, several years before Registered Mail was adopted.

In the Postmaster General's Report of November 17, 1828, Mclean wrote that "It may be advantageous to the public and the department at some future time, for it to become the insurer of moneys transmitted in the mail, being authorized to charge a higher rate of postage in such cases to indemnify for the risk incurred. To guard against frauds, this responsibility must necessarily be limited to packets mailed at principal offices, under such regulations as shall afford the greatest possible security"