I can’t find anything about it on line, But my yahoo account now only has about a months worth of messages in my sent folder. I’ve been keeping about 15 years of messages in there as an extra address book, and know it is all gone.
Mine goes back to when I created the account in 2006.
I just looked and I have sent items dating back to 2007. I’ve had my email address linger than that, but I’m not sure whether older ones were dumped by yahoo, or by me.
i’ve got email from the last century when we tied onions to our belts, which was the style at the time.