As you’d expect, the volunteer team of rogue archivists known as Archive Team are working hard to preserve as much of Yahoo! Groups as possible before its shutdown.
Their initial crawl discovered nearly 1.5 million groups with public message archives that could be saved, with an estimated 2.1 billion messages between them. As of October 28, they’ve archived an astounding 1.8 billion of those public messages.
From The Deletion of Yahoo! Groups and Archive Team’s Rescue Effort by Andy Baio