Yahoo has made the decision to no longer allow users to upload content to the Yahoo Groups site. Beginning October 28, you won't be able to upload any more content to the site, and as of December 14 all previously posted content on the site will be permanently removed. You'll have until that date to save anything you've uploaded.

In the groups it is lot of old valuable content, like some discussions about problems with old gear and so on.

This is why you need to understand that corporation is made only to bring profits and absolutely do not care about your work value, value of data to society or anything even remotely related to moral.

Sadly, it is low probability that someone will erase all Yahoo management and owners first, before December 14th, but we can hope.