Usually I don't buy vintage postcard without postmark but there are exceptions of course. For example, when I see a lovely Santa postcard from a reliable seller, like this:
When there's no postmark or stamp which can help me to identify the card's age, then I can give just a rough estimation.
As for this card, I know that the printer was the German ROKAT company and they used this type of logo before the WW2.
Since my card has no undivided back, I'm sure this is printed after 1907. And since my card has a white border, I'm sure my card was printed between 1916-1945.
So my card is definitely a vintage card :-)
You can find my other vintage Christmas cards on the label 'old Christmas cards' on the sidebar.