Do the misspellings on the packages have any significance?
https://www.businessinsider.com/cnn-bomb-to-john-brennan-wasserman-schultz-misspelled-on-envelopes-2018-10
One addressed to former CIA Director John Brennan, which Business Insider has seen pictures of, misspelled his name "Brenan" and mistook the TV network he contributes to.
NBC News reported that one sent to former DNC chair Debbie Wasserman-Schultz had her surname spelt "Shultz" and spelled Florida, her home state, as "Florids."
Wasserman-Schultz was reportedly listed as the sender on all the packages, and is said to have received a package meant for Holder which got sent to her after a failed delivery.