We like to think that the emails we get are private and only we can read them.
There is a long list of readers before you get it.
1 Government agencies
Prism is one of the best examples of email scanning.
From the Snowden leaked presentation you can see they started to read your Yahoo email since 2008.
2. Yahoo itself
Oath, the company that owns Yahoo, does not keep that in secret.
And it does not matter if you have the free or paid account if you do not opt out from this feature Yahoo will scan them.
Yahoo does scan only promotional emails you receive like newsletters, to understand what are your preferences and profile you.
Consequently, the data is sold to advertisers that will use it to create the relevant advertisement for you advertisment for you. Great right?
Fortunately you can opt out with just a click.
Well then you, of course, read your emails.