Café De Post is one of the main gathering places in Dokkum's historic centre, a grand café in the Dutch provincial tradition occupying a prominent position on the main square. The terrace fills on any day with reasonable weather; inside, the room is comfortable year-round.
The menu covers the expected ground — sandwiches, soups, Dutch lunch standards, and a selection of cakes. The Frisian sugar bread (suikerbrood) is worth ordering if it's available — a sweet, dense loaf studded with pearl sugar. Coffee and tea are served throughout the day; beers and wines in the evening.
This is the kind of place you end up at twice in a one-day visit — once for coffee in the morning and once for a beer in the afternoon. There are worse patterns.