Have your friend appeal it. I had a ban reversed after somebody used my computer to make a bunch of accounts to harass somebody else on the site. I explained the situation as best I could and made a point to change the email attached to this account and the password(and all my other passwords!).
My first support ticket got lost, so I sent another one with the same contents after a month of nothing, and the ban was taken off on the condition that I would be re-banned if my IP showed suspicious activity again.
I wasn't mad at all because I can TOTALLY understand why they banned me. I blame myself for not being more vigilant of what this person was doing. They CLAIMED they used my computer to job search. Anyway, said guilty person is no longer allowed near my house.
DA doesn't accept screencaps of stuff as evidence, but I might be wrong and that might only be when reporting another deviant, so try it anyway. Try to be really concise when you write the support ticket because people have to rifle through several a day, and I don't know if they'll sit down to read something that's ten pages long.
Thanks... But in this case, there was a female dA user who blocked him, and the reason my friend got banned is because some troll used a slightly re-typed version of my friend's dA username and send a hate note to her, meaning that "suspected" user tried going around the block.
I know this because me, my friend and the female dA user who reported my friend all know each other. They got personal issues, but when we chatted via Skype we got news from her that she didn't had anything to do with this.
Yeaaaaaah, I think sharing that evidence with the staff might help. I think DA can track the IP of a username when it first signs up, but that might not matter if somebody uses a proxy. I don't really use them myself and am not quite sure how they work. But links to the banned friend and the fake username might shed some light on the error.