The address block design (for the destinations) follows exactly a very peculiar address block design for those same addresses that was published on the internet at the Jews for Life website.
(At USPS Headquarters we were able to find those addresses just moments after the first pictures were released by the FBI. I suspect they paid no attention to us.)
Why don't you provide some information so people can figure out what you are talking about. The destination addresses on the envelopes looks like a typical way of writing a destination address. There's nothing unusual about it. You can do a Google search and find any number of envelopes which are addressed in the same way, even instructions for addressing letters that way It's probably the way most people address envelopes.
The RETURN address on the Senate letters was: "4TH GRADE, GREENDALE SCHOOL, FRANKLIN PARK, NJ 08852".
There is a Franklin Park in New Jersey, but there is no Greendale School anywhere in New Jersey. 08852 is Monmouth Junction, about 5 miles from Franklin Park.
Instead of playing games with the ZIP code to make things fit your beliefs, why not just look at the FACTS. The ZIP belongs in the same area, but everything is scrambled. Why? Evidently, to make certain that the anthrax-laden letters wouldn't be returned to a REAL school.