Apparently, there is some semi-obscure tradition that God answers prayer requests if they are written down and stuck in the cracks and chinks in a Jerusalem wall. Apparently, even if God is omnipotent and omniscient, he won't see/read/hear your prayers unless you've taken the time and effort to get your request to the proper authorities (Israeli postal clerks, apparently), who will then proceed to deliver them to God (via a wall?)
I don't know -- it all seems a little hokey and contrived to me. Why would letters stuffed in the cracks of a wall (not just any wall, but the crumbling outer retaining wall of Jerusalem's Jewish Temple) be answered?
According to Rabbi Shmuel Rabinovitz, prayers of people all over the world “ascend through this holy place.”
Huh? A prayer said in earnest 10,000 miles away has to travel (apparently on paper) to this wall just to be heard by an omnipresent deity?
I have to wonder if any of the rabbis or letter writers have bothered to think through the implications of their bizzare rituals.