The ones dropped into the mailbox aboard the ship don't get mailed/postmarked until you're back in home port. At least they didn't for our first 2 cruises. Sooo, we like to purchase stamps and mail the cards ourselves while we're ashore. CAUTION: a block of 6 POSTCARD stamps in St. Maarten cost me 10 bucks US. Enough to make me go.......well.......POSTAL!