Git is a really great format for email archives, because it provides free duplication and compression via packfiles, although I think it is a tilting at windmil

Git is a really great format for email archives, because it provides free duplication and compression via packfiles, although I think it is a tilting at windmills to try to map specific commits to emails. I explained my git/imap workflow in another comment here. However, git is perfect for calendars. It is used as a backing store for these caldav servers: https://github.com/jelmer/xandikos https://github.com/jelmer/xandikos https://github.com/Kozea/Radicale https://github.com/Kozea/Radicale