About five years ago, I purchased the identical Babe Ruth signature from a dealer. However, mine was on a piece of paper and not an envelope. Luckily, about a year ago, Terrier, Richard Simon, and PSA/DNA told me that it was not authentic and I was able to return the Babe Ruth autograph to the dealer for a refund. The dealer was able to get their money back from filing a claim with their insurance company.
Somehow the forgers appear to be able to run copies or use a machine to produce the exact same signature. Here is a scan of the one that I previously owned. Judge for yourself: