The spokeswoman said MyLotto sends an email to all players who win a prize over $1,000 letting them know that they have a prize to claim.
"[But] some customers do not check these emails, preferring to find out whether they are a winner when they next log in to their MyLotto account.
"As a result, we don't know at this stage whether the winner knows just how lucky their ticket is!" she said.
This was the 12th time Powerball First Division has been won so far this year, following on from a $16.5 million Powerball win last month.
The Auckland man, who picked up his lucky ticket in Wellsford, plans to use the winnings to buy his first house.
Three other Lotto players from Silverdale, Nelson and Dunedin will also be celebrating after winning $250,000 with Lotto First Division on Saturday.
The winning Lotto tickets were sold at Pak N Save Silverdale, Nelson City New World, and Gardens New World in Dunedin.
The "luckiest" year on record for Powerball players was last year, where Powerball First Division was struck 15 times throughout the year.
However, 2019 is on track to be one of the "luckiest" years for Powerball players, with Powerball First Division being struck 12 times this year to date.
Saturday's win is the 17th time a MyLotto player has won Powerball First Division and is the eighth largest prize won on MyLotto.
Strike Four rolled over and will be going for $400,000 tonight.
• Anyone who bought their ticket from any of the above winning stores should write their name on the back of their ticket and check it immediately in-store at any Lotto shop, online at MyLotto.co.nz or through the Lotto NZ App.