One thing that now becomes clear: EU countries may be divided (re electoral rolls) into "automatic" and "declarative" categories. One group (that includes Sweden) derives its electoral lists automatically from other sources (taxation rolls, or residency rolls), the other, from individual inscription by voters (example, France).

Those who reside in an "automatic" country are much more likely to receive useful information (as with the forms sent out in Sweden), than those in "declarative" countries (in France, my impression is that if you don't go to the town hall and pester them, you won't be told anything).