Our church provides a stack of postcards on the 'welcome' table that are stamped and address-labeled for the various sons/daughters/nephews/grandchildren of the church that are abroad. It helps because it takes so little time and effort to write a postcard-length message even if we don't know him. I sometimes just write something like, 'The azaleas are starting to bloom pink, and the forget-me-nots are out; robins are everywhere. Be well. You are much in my thoughts!'