We don't have a lot of details, but if you're in the United States, the answer is probably yes. There are rarely any meaningful rules of evidence in student misconduct cases, so pretty much anything can come in.
There may be some small difference in the answer depending n whether you're dealing with a public university or private, but in either case, I can't think of any reason why they would not be able to introduce the evidence if they had it.
If there's a question about its authenticity, I imagine that would just be up to the misconduct board to decide. If Person X says "Person Y sent this to me," and Person X seems credible, that's probably going to be enough.