https://workspace.google.com/blog/identity-and-security/an-overview-of-gmails-spam-filters
User feedback, such as when a user marks a certain email as spam or signals they want a sender’s emails in their inbox, is key to this filtering process, and our filters learn from user actions.
Maybe a lot of people just mark it as spam for some reason, wonder why that could be? Could it be because they simply don't like your emails and think they feel spammy? No, that couldn't be it, it has to be that the same company that kissed up to Trump also just hates republicans now for some reason! /s
Great article, would highly recommend anyone with the time give it a full read through.
Wikipedia is incredibly valuable, and insanely well edited and put together, and we're all lucky to have something like it available for free.