Hunter Biden introduced his father, then-Vice President Joe Biden, to a top executive at a Ukrainian energy firm less than a year before the elder Biden pressured government officials in Ukraine into firing a prosecutor who was investigating the company, according to emails obtained by The Post. The never-before-revealed meeting is mentioned in a message of appreciation that Vadym Pozharskyi, an adviser to the board of Burisma, allegedly sent Hunter Biden on April 17, 2015, about a year after Hunter joined the Burisma board at a reported salary of up to $50,000 a month. “Dear Hunter, thank you for inviting...