Oath, the Verizon subsidiary that owns both AOL and Yahoo “has been pitching a service to advertisers that analyzes more than 200 million Yahoo Mail inboxes and the rich user data they contain.” This data is then used to figure out what products and services to target its users with. The pitch also broadens out to bring AOL users’ emails into the fold...  Read more at Mashable.

To opt out, you have go to Oath's Privacy>Controls page and follow the links for either Ad Interest Manager (Yahoo) or Opt-Out of interest-based advertising (AOL) and follow the instruction...