Coincidence? in 1700 polish privateer frigate same named: Postillion - Pocztylion under captain Kornelius Nevell take swedish prize near Karlskrona and bring it to Gdansk . Next year 2 Swedish vessels damaged Postillion near Gdansk and ship lay on shallows. You sure it was danish ship? Maybe just same name,,,sadly cant find any plans for this one. But it is named in polish ship list: http://www.polskieokrety.republika.pl/1650%20-%201720.htm