Lyndon, Seeing as the folks who set up the original distribution are on the Yahoo list it's the best place to ask questions. I assume you don't want to set up a Yahoo account? Facebook perhaps?
I did fight my way thought the Yahoo interface to get onto at least one of the MTS groups via the mailing list interface. But after falling off that a couple of times, for unknown reasons, I gave up. And as I mentioned, the Yahoo Groups web interface is just too horrible to contemplate.
And no, I don't do Facebook, either. But that wouldn't make a difference in this case.
I pine for the simplicity of mailing lists. Then again, Yahoo, as co-instigators of DMARC, are ensuring the end of mailing lists as we've known and loved them for the past three decades.
--lyndon