The tabloid was the only national paper in Britain to not mention the killing of 50 people in the shooting at the LGBT Pulse club in Orlando, that also left 53 injured. Most papers dedicated most of their front pages to it.
But The Mail instead went with a story about a "plot to let 1.5m Turks into Britain". Its strap line was about the Queen's official birthday and an offer of a free pair of earrings like hers.
The first edition included a double page spread on the tragedy on pages 10 and 11 but moved it to pages four and five for the second edition.
Roy Greenslade, media columnist for The Guardian who has worked across Fleet Street, wrote: "As news judgments go, the call by whoever was editing the Mail on Sunday evening must rank as one of the most eccentric in the paper’s history."
Greenslade noted the Daily Express and Daily Star also led on different stories - the Express on "fury" at the latest Brexit argument and the Star on claims England could be disqualified from Euro 2016 if fans continue to misbehave.
Both papers still mentioned what happened on their front pages.
Greenslade wrote: "What world do those three editors inhabit? How could they not realise the significance of what happened in Florida?
"We are used to weird editorial decisions by the Express and the Star... But the Mail is a different matter altogether. Whatever you may think of its political and social agenda, this is Britain’s second-highest selling national title. It usually exhibits an acute news sense. Why did it desert it this time?"
He called the decision a "mix of commercial cynicism and Eurosceptic fanaticism".
Other journalists, included Jeremy Vine, noted the Mail's failure to put it on its front page. Vine called the omission "amazing".
Others also noted the omission:
TV presenter Kirstie Allsopp also took issue with the Mail:
While readers pointed out the Mail had a right to print what it wanted, Greenslade replied: "They are free to get it wrong and I'm free to point it out."
HuffPost UK has requested comment from the Daily Mail.