I can't point to a single piece of evidence that you can see, but I can point to evidence that does exist, but it exists in a black box.
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I do not know what the evidence is, but I do know that two people filed a FOIA request about the specific subject of Donald Trump and the Hillary Clinton e-mails involving the July statement where Donald Trump asks to the media in general someone should hack the Clinton system and reveal these e-mails.
The two people are
Ryan Shapiro who is a Ph.D. candidate at MIT and FOIA expert
Vice reporter Jason Leopold (and if you want to make him look less serious you instead call him a buzzfeed reporter for he has sold some articles to buzzfeed)
Yet the FOIA request was denied for there is still an active investigation in this manner. Where and how the investigation consists of we really do not know.
Thus you only see the very left and very right newspapers and blogs commenting on it. Such as The Daily Caller (aka Tucker Carlson's rag), ShareBlue (a very left leaning blog / news site) and so on for right now we do not have hard news on the subject, instead we just know there is something in a black box but we do not get to see what is in the black box.
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So can I prove it, no. Can I point to a black box that may contain evidence yes.
That black box may be anything though, thus you will see lot of conspiracy type theories for we can't prove a negative, but conspiracy nuts like to try to prove a negative and thus they create grand theories about it.