Trump in recent days has drawn attention to the new revelations from the Post, something that drew criticism from Schiff.
“The origins of this whole smear are from the Kremlin and the president is only too happy to have Kremlin help in trying to amplify it,” he said Friday on CNN.
The Associated Press reported that the FBI is investigating whether the emails are tied to a foreign influence operation, although the exact scope of what was being investigated was not clear.
Schiff was one of the key figures in both the investigation into allegations about Russian interference in 2016 and the 2019 impeachment hearings, and has a history of making dramatic claims about President Trump’s alleged ties to Russia.
The Wall Street Journal editorial board in May accused Schiff of spreading "falsehoods shamelessly about Russia and Donald Trump for three years even as his own committee gathered contrary evidence."
On Friday, Schiff said that Russia has an "obvious interest" in denigrating Biden and wants Trump to win.
"I think we know who the driving force behind this smear has been all along, it's been the president and the Kremlin," he said, calling him "the gift that doesn't stop giving" for Moscow.
The Associated Press contributed to this report.