Do you have any examples?
I took a random file uploaded on 2014-02-01, which was about when we switched attachment uploading to DevHost, and the file appears to be alive.

https://en.wikipedia.org/wiki/NZB

In short, you'll know if you use newsgroups.

AnonFiles isn't the only host that we wrap files in 7z though, so it isn't really appropriate there.
I'm guessing WinRAR 3.93 is actually the minimum version which supports all current 7z encodings, was released over 3 years ago, as was 7-Zip 9.20. I think there can be a reasonable expectation that people aren't using ancient software, especially considering that a lot of anime is released in Hi10P, which mainstream support for only came out in late 2011 (and we don't provide assistance on how to play it back).

But regardless, there has always been a note about it in the FAQ page.
Does that seem alright?

I wonder what is NZB? i can't download from there

well, add that to the AnonFiles Corruption Page cause it help a lot for who dont know about that.

It seems no Attachments file uploaded in earlier release.
I wonder if it's  problem with Dev-Host or something else.
I Hope it'll be fixed already.
Arigatou admin-sama.
:)