Postcards were the emails of generations ago.  Like an email's unwritten rule that the message should be short, a postcard allowed only so much room to write something, all the while giving a glimpse of where one was with an image.  There are a few online collections of older Basque postcards, and places where you can also purchase current postcards.

Samples from www.pagesjaunes.fr (select department 64 for the Basque Country)

Samples from the Special Collection at the University of California, San Diego at http://orpheus.ucsd.edu/speccoll/swpostcards/dp302.b53_e78_1937_1.html

Sample from www.cafepress.com/+basque+postcards:

Samples from www.zazzle.com/basque+flag+postcards: