The new Yahoo Mail, which everyone is getting whether they like it or not, comes with an added bonus along with the slick new interface, ad targeting.
Like Gmail, Yahoo Mail can now scan your messages and display more relevant ads based on the contents.
This isn't much of an issue, no one actually reads your messages and the same automated scanning is done by every email provider, to filter for spam for example.
Still, if the feature worries you, there's an opt-out button and it's quite easy to use. All you have to do is visit Yahoo's Ad Interest Manager and click on the big "Opt Out" button next to the Interest-based Ads box.
Alternatively, users can opt out of individual interest categories. These settings apply to all ads on Yahoo sites, not just the new Mail.