I've been to Breitbart occasionally to read an article or two that was linked from somewhere else, but never given them any contact information. The only ways I can think of that they would have gotten my mailing address would be from voter registration records (I was Republican before reregistering Unaffiliated) or from one of several gun rights organizations I belong to. Maybe it's the NRA.
Then it’s as big a mystery as we getting begging SPAM from Carson on cell phones! I almost NEVER even turn mine on, nor do I use it to post here, etc.!