Blocking
Yahoo states that to block, there is an option in settings. This is untrue, there is no option for more settings thus no option to block when using the app or yahoo mail website. A specific option for blocking phrases and addresses would be really useful and should really be standard. Currently there is no option to block. Marking as spam isn't working. I am constantly being spammed.

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Ian Dugdale commented
Agreed all marking spam does is delete the email
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Sabamika commented
Thing is, there actually is a way to block email addresses. It's already been a thing. The problem is it's somehow still useless. On a free account, you can only block one hundred email addresses. To do more, you'd have to pay for premium.
And while Yahoo won't like this opinion. Their premium email service isn't worth paying for.