The SmokingGun.com Web site was behind the experiment to see what censors would allow -- or miss -- at the Photostamps.com Web site.
"We thought there would virtually be no way they can police these things," Smoking Gun co-founder Bill Bastone told the New York Daily News.
In addition to the Unabomber, stamps were allowed to be created featuring former Yugoslav President Slobodan Milosevic, who is now on trial for genocide and war crimes. The experiment also successfully created stamps of executed spies Ethel and Julius Rosenberg and White House intern Monica Lewinsky's infamous stained dress.
However, the censors did spot and veto a stamp of Lee Harvey Oswald, the newspaper said.