[Question]: What for sending X-USER-EMAIL ?

[kohheepeace]

Hi, @adamniedzielski Thanks for your great work!

Is sending X-USER-EMAIL is for mitigating timing attacks? (as described below)
https://gist.github.com/josevalim/fb706b1e933ef01e4fb6

And I also see the below issue to remove secure compare code
Remove unnecessary secure compare

So, my question is what for sending X-USER-EMAIL ?