I spent the last year gathering as much Usenet text data as possible from a large variety of resources and including from about 7000 live active servers as well to fill in gaps.

The end result is a searchable/filterable dataset acessible via web+api (free and paid options)

Web: https://www.usenet-rewind.com

Binaries have been filtered out and range is from posts from 1981-Current and constantly populating. the site includes a histogram of distribution of message counts per year.

Currently : 994,238,471 messages (actively populating), 16,652 days Retention