I found an article in the recent winter 2010 Volume 11 issue of the American Ancestors (which until recently was called New England Ancestors). The magazine is published quarterly by the New England Historic and Genealogical Society (NEHGS). The article was by James R. Miller and entitled Philatelic Genealogy Update. The article was a followup to one in the 2009 Volume 10 issue entitled Philatelic Genealogy: Old Envelopes, Postcards, and Immigrant Origins.
Mr. Miller, an American, has spent the better part of the past several years in Haguenau, France researching his own families of the region, which is near Strasbourg in Alsace Lorraine. His wife has written 10 books on the area, while he has performed major and innovative research. He also runs the web site Philgen.org. That site has many envelopes and postcards which contain or infer genealogical information. Mr. Miller takes each contributed and accepted item and attempts to provide a tie-in to a Census, Ancestry.com family tree or other data. Often the effort identifies an immigrant ancestor’s birthplace, a family’s migration after their arrival or the location of siblings.
These old envelopes and postcards exist in many seldom reviewed boxes in our attics, on E-bay and other auction sites, and with stamp collectors.
Give philgen.org a try. It is an unique source of possible genealogical information.