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Lots of players have been getting screenshots of players harassing them or well.. anything. Staff can't really do anything unless it's screenshotted. Now then, you can't just keep the screenshots and say you have them, that doesn't help at all! So post the screenshots and PM (it means private message, emphasis on PRIVATE) on anything that you can post images on, as long as tons of people won't see it. I would recommend something like imgur, then you can delete it after. Not many people know about it, so I thought I would let you all know. Anyways, I hope that this doesn't become a further problem.
Edit: Send the screenshots to me PM via MineCats Discord. That's where I'll most likely see them.
To access your screenshots:
Go to %appdata%
Click the file titled, ".minecraft"
Find the screenshot you took, and you can use it.
I hope this was helpful to you, as I feel it'll be very helpful to us staff who need screenshots!