Shipmail
The objective of shipmail is the transport of mail by means of commercial vessels: liners, cargo boats, ferries, scientific ships (in Antarctica) ... Here are some examples of such covers.
letter with mark PAQUEBOT and postmark from Belize (Central America)
letter with the label of the liner Jean Mermoz and blank slogan box to right from Marseille
letter posted on board of the liner MARION-DUFRESNE and postmark Marseille paquebot
letter with labels PAQUEBOT and M/S KINGSTOWN and postmark from CURAÇAO (West Indies)
letter with the label «Posted at sea» on the liner France and illustrated slogan to right of date stamp from Le Havre
Letter posted aboard the liner FRANCE (see reverse) and postmark SOUTHAMPTON paquebot
Reverse side of letter
Clicking on the image reveals the other side of the envelope