Wouldn't "JRB3" mean Joseph R. Biden III a/k/a Beau Biden? He was alive then. He died in May 2015.
It does. Joe Biden is a Jr. and Beau was the third. Middle name: Robinette.
That's interesting and all, but "JRB3" is Joseph R. Biden III, called Beau. At the time of the email, he was still alive. He died 5-1/2 years ago in May 2015.
He attended University of Pennsylvania ("Penn").
You won't find much activity online from him recently. Nice dig, though.