For mail lovers of course this tall ship is a favourite one, as this ship was meant and used for mail transport:

The word 'tall ship' (in Dutch also in English) I heard for the very first time just two years ago, when the event Sail Amsterdam took place. I didn't have time to visit the event, but friends who did, told me they were impressed by the amazing tall ships, and they showed me beautiful photos. So hopefully I can take a look next time, in 2020 that will be.
This stamp sheet, Dutch PostNL issued in honour of the Maritime Museum in Rotterdam, shows one - tiny! - tall ship, see bottom right:

A similar old tall ship has been pictured on this recent stamp, part of a six stamps sheet connecting the Netherlands and Australia:

A tall ship (in Dutch also 'zeilreus', 'sail giant') is a large, traditionally-rigged sailing ship. I though it always has more than one mast. So I am not sure if the following, modern, vessel will belong to this Sunday's theme. At least she sails over the oceans, and is underways for a very long time, an amazing journey. On this stamp sheet, issued by PostNL in 2015, you can see the vessels and sailors in action:

See more stamps on this interesting theme at and via Sunday Stamps.