The FBI is saying Papadopolous is a liar. The Professor said he is a liar. Nobody ever heard of the guy, and he was a volunteer, but the best part is..... This little weasel tried on a few occassions, NO DOUBT WITH MUELLER'S DIRECTION to try to get THE TRUMP CAMPAIGN to meet with people with Russian Associations, and MANAFORT for the 2 short months he worked for THE TRUMP CAMPAIGN REJECTED ALL OF THOSE REQUESTS.!
Whether or not he's a liar, his emails do not lie. He has emails between himself and his Trump campaign handlers, in which they both approveed and encouraged his contacts with the Russians.
The only caveat is that they wanted somebody low level, to give them plausable deniability. They didn't want "DT" to go to Moscow, because it might look like the collusion it was.