There's a Talking Points Memo article that adds some intrigue into how Fox News even got this email. I'm not going to link to it because I'm on my phone and don't want to mess with it, but here's a quote:
"Fox News reported that Trump attorney John Dowd made the statement in an email to a Wall Street Journal reporter who wrote about the Manafort raid. But two Journal reporters who wrote about the raid told TPM they hadnt received such an email from Dowd."
TPM also reached out to the attorney himself, who said he was "tired out" and basically gave a no comment. Kind of an odd situation.