Despite Yahoo offering @ymail.com and @rocketmail.com email addresses (which they are probably doing because there are no good names left especially with all the spammers registering bogus names).
When you want to check email, you don’t get on the first load. You have to click on it, because you are shown a newsblock first.
This is done for 2 reasons
- It’s another pageview
- There maybe some news headline that catches your attention and bring you to news.yahoo.com
However, Google knows you login to your mailbox to read email, not news.