Political emails tend to get tagged as spam in general. I have someone close to me who is involved in local Democratic Party and progressive organizations. When you go to an event or donate money (say an award banquet), they share your name and spam the crap out of you. A lot of that mail gets tagged as spam as a result.

Conservative outlets work similarly, but they seem to have bigger online operations and are hard to get out of. My in laws get barraged with this stuff, and a mail provider like GMail or Microsoft gets a lot of spam signals from it I’m sure.