How to sort an object using array of objects

Question

let object = {
  'demo@gmail.com': [
    {
      a: 5,
      name: demo
    },
    {
      a: 4,
      name: demo
    }
  ],
  'demo1@gmail.com': [
    {
      a:2 ,
      name: demo1
    },
    {
      a: 1,
      name: demo1
    }
  ]

}

Expected output:

I am trying to write an function to sort an object like this

But i found it is difficult.can anyone can give me some hints to write such function? i need it to show the grouped messages

let object = {
  'demo1@gmail.com': [
    {
      a:2 ,
      name: demo1
    },
    {
      a: 1,
      name: demo1
    }
  ],
  'demo@gmail.com': [
    {
      a: 5,
      name: demo
    },
    {
      a: 4,
      name: demo
    }
  ],


}