The draw, which rose from $US667 million on Tuesday when no one had the lucky six numbers, will take place on Friday.
The prize is the second-largest jackpot in US history, behind only a $1.6 billion Powerball prize won in 2016.
Mega Millions is played in 44 states, Washington, D.C., and the U.S. Virgin Islands.
The email claims the recipient was among a group of randomly selected people to participate in an ongoing Mega Millions drawing and then solicits personal and financial information from the recipient. The amount you will win is likely $0, because the odds of winning either jackpot are one in several hundred million.
Information from the Associated Press was used in this report.
Dreams of being a billionaire are now in reach, thanks to the Mega Millions.
Nine Mega Millions tickets from Tuesday's drawing matched five white balls to win the second prize - $1 million.
But when it gets close to $1 billion, even he can't resist, knowing he just bought the winning ticket.
However, its second-biggest one of all time for $656 million happened in 2012 before the tweak.
Good people of America, the lottery jackpots need to be stopped.
Officials were anxious that the relatively smaller but more frequent prizes - a "paltry" $100 million, for instance - would result in "jackpot fatigue", which is why they tweaked the game past year, Medenica said.
Nobody matched all six Powerball numbers during Wednesday evening's drawings, so the jackpot rolls again.
Reducing the number of balls for the first five numbers increases the chances of winning a smaller prize.
The winning numbers were 3, 57, 64, 68, and 69. Michigan Lottery said the majority of tickets for a jackpot are purchased on the day of the drawing.