The TRULINKS system is the inmate sets up, sends an "invitation" to a person's email of his choosing, they click accept (or ignore), and then they are allowed to exchange email (that is monitored). As far as snail mail - caution to those wishing to send him fan mail the likes of "You kick ass DPR we love you yayyyy you're a fucking rockstar of drugs woohoooo fuck the government fuck the feds!!!" type of letters. Do not do that. That mail is monitored, it is not private, and can be used against him in the investigation and/or trial. Anything sent to him that explicitly refers to Mr. Ulbricht as DPR can not be helpful at this point, given he has twice denied the charges infront of a judge and magistrate.