The fine print (indeed in small, grey font) says:
To opt out of interest-based and contextual-based advertising resulting from scanned and analyzed communications content, click here.
For instance, we scan and analyze email messages to identify key elements of meaning and then categorize this information for immediate and future use.
Hmm, somehow the first summary says scan and analyze yet does not say retain, nor does this say which key elements of meaning are retained. Clearly one can presume these days this means email headers so clearly one can see how they can have a nice database of who I talk to, presuming these people don't use aliases, and usually these headers include things like IP addresses and OS choices, etc. In fact the page goes on and says just that.
How does one get around this?
Mail Help says:
Download your Yahoo! Mail using IMAP: IMAP allows you to access your email from a different email program, such as Outlook, Mac Mail, or your mobile device’s application. You can download your data to your personal computer or device using an IMAP program. However, in order to continue using Yahoo! Mail you will need to accept the Communications Terms of Service.
I didn't see there where it said it would scan/analyze/retain any of my email data or metadata.
Yahoo! automatically receives and records information from your computer and browser, including your IP address, Yahoo! cookie information, software and hardware attributes, and the page you request.
Yahoo! uses information for the following general purposes: to customize the advertising and content you see, fulfill your requests for products and services, improve our services, contact you, conduct research, and provide anonymous reporting for internal and external clients.
Ahh, "research". Wonder how they define that?
And of course the obligatory:
We respond to subpoenas, court orders, or legal process, or to establish or exercise our legal rights or defend against legal claims.
Pretty much makes me an open book, no?
So it seems the only decent choice for privacy is to just say goodbye to Yahoo.
Seems one can spend $19.99/year for mail plus and put in a forwarding rule if that matters enough to do.