gayrightsactivia:

Another day, another turned on by default notification feature that no one asked for. If you, like me, have been puzzled by tumblr sending you push notifications to let you know a mutual has made a post, the above is the reason why. You can find this in settings under notifications.

You no doubt know the rest at this point because this is like the 6th feature in a row you need to disable to keep this blue dumpster semi usable.