It had all the attributes of a Russian disinformation: found by a right-winger coming up with a strange story; brought by Giuliani (known for misinformation and his pro-Russia informers), only given to one single biased right-wing media, and not to all media, no metadata, etc... if the disclosers wanted to make it look like a disinformation, they could not have done it better!
Not to mention the reputation of Trump and the right-wing from diffusing fake news and conspiracy theories: birtherism, pizzagate, etc..., including coming from Russia (INC/Crowdstrike). Not to mention either the Russian attempts to influence the previous elections.
When people have a proven record of lying, they should be surprised when no one believes them.