The no-cost migration doesn't allow the Yahoo message archive to be added to the Messages page here due to formatting issues. Instead I've uploaded HTML digest files of the complete Yahoo message archive from message #1 through yesterday in the Files section here:
/g/C-N-R/files/Yahoo%20messages%20archive
The PG Offline 4 software I'm using won’t let me put all the messages in one huge archive, but the file would be quite large and take ages to open anyway. I compromised at 4-year digests. You can open, view and search the digests in your browser. You can also downlaod the HTML files.
I hope this is of some use at least!
Pete