As others suggested you don’t need all your historic mail on your mailserver. My approach to email archival is the same as all my historic data — a disorganized dumping ground that’s like my personal data lake, and separate service(s) to crawl, index, and search it (e.g. https://www.recoll.org/)
Don’t contact the company. They’re breaking the law, and they know it. Report straight to the regulating authority.