I'm about to finish my undergraduate degree in mathematics in France, and expect to be close to the top of my class in a top university here. Next academic year, I will be studying for a master's at UPMC (Pierre and Marie Curie University). I intend to apply for PhD programmes in the US or the UK.
Since I will be only a few months into my master's program when I apply, I expect that some of my letters will be from my undergraduate professors. The head of the math department and a professor I've had for over a year said they would write letters for me, but neither one of them have published anything in the past decade.
How much value is given by the admission program to a letter of recommendation written by a teacher at a foreign university?