A "Southern Letter Unpaid" cover sent from New Orleans, Louisiana to Paris, France is valued at $30,000-40,000 ahead of a sale at Robert A Siegel in New York.

The lot is one of the highlights of the Benjamin Wishnietsky Collection of Confederate States Postal History auction on February 26.

The Southern Letter Unpaid handstamp was created in 1861

Following the outbreak of the American civil war (1861-1865) a suspension order passed on June 1, 1861 barred post offices from forwarding mail from northern US states to those in the south, although it was still possible to send mail from the south to the north through Louisville, Kentucky.

On June 24, the office at Louisville was ordered to remove all postage from the letters travelling north, an insurmountable task given the sheer volume of mail.

In response, the postmaster created a unique handstamp, reading "SOUTHN. LETTER UNPAID", that allowed stamps to be invalidated quickly.

This cover, one of 29 known examples featuring the handstamp, was able to travel between the US and France without the need for postage to be paid until its arrival in Europe due to a longstanding treaty between the two nations.

It also features datestamps from New Orleans and Paris, along with three cent and 12 cent US stamps dating to 1861.

We have a range of rare stamps available to purchase.

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