Custom E-mail notification

Which email do you mean? For example, the emails sent by process model alerts cannot be customized.

Are you talking about email sent from Send email Node in process?

The email that comes when the process model got fails

The email that comes when the process model got fails

essentially the error message towars the admins/designers -> no customizing possible 
But you can see the environment name by hovering about the link in the bottom section.

{
  a!localVariables(
    local!rows: a!forEach(
      items: enumerate(50) + 1,
      expression: {
        id: fv!item,
        selected: false,
        value: "Value " & fv!item
      }
    ),
    a!formLayout(
      label: "Editable Grid with Checkboxes",
      contents: {
        a!gridLayout(
          label: "Grid",
          data: local!rows,
          columns: {
            a!gridColumn(
              label: "Select",
              value: a!checkboxField(
                label: "",
                labelPosition: "COLLAPSED",
                value: a!forEach(
                  items: local!rows,
                  expression: fv!item.selected
                ),
                saveInto: a!forEach(
                  items: local!rows,
                  expression: a!save(
                    local!rows[fv!index].selected,
                    fv!value
                  )
                )
              )
            ),
            a!gridColumn(
              label: "ID",
              value: a!textField(
                label: "",
                labelPosition: "COLLAPSED",
                readOnly: true,
                value: a!forEach(
                  items: local!rows,
                  expression: fv!item.id
                )
              )
            ),
            a!gridColumn(
              label: "Value",
              value: a!textField(
                label: "",
                labelPosition: "COLLAPSED",
                value: a!forEach(
                  items: local!rows,
                  expression: fv!item.value
                ),
                saveInto: a!forEach(
                  items: local!rows,
                  expression: a!save(
                    local!rows[fv!index].value,
                    fv!value
                  )
                )
              )
            )
          }
        )
      },
      buttons: a!buttonLayout(
        primaryButtons: {
          a!buttonWidget(
            label: "Submit",
            submit: true,
            style: "PRIMARY"
          )
        }
      )
    )
  )
}

{
a!localVariables(
local!rows: a!forEach(
items: enumerate(50) + 1,
expression: {
id: fv!item,
selected: false,
value: "Value " & fv!item
}
),
a!formLayout(
label: "Editable Grid with Checkboxes",
contents: {
a!gridLayout(
label: "Grid",
data: local!rows,
columns: {
a!gridColumn(
label: "Select",
value: a!checkboxField(
label: "",
labelPosition: "COLLAPSED",
value: a!forEach(
items: local!rows,
expression: fv!item.selected
),
saveInto: a!forEach(
items: local!rows,
expression: a!save(
local!rows[fv!index].selected,
fv!value
)
)
)
),
a!gridColumn(
label: "ID",
value: a!textField(
label: "",
labelPosition: "COLLAPSED",
readOnly: true,
value: a!forEach(
items: local!rows,
expression: fv!item.id
)
)
),
a!gridColumn(
label: "Value",
value: a!textField(
label: "",
labelPosition: "COLLAPSED",
value: a!forEach(
items: local!rows,
expression: fv!item.value
),
saveInto: a!forEach(
items: local!rows,
expression: a!save(
local!rows[fv!index].value,
fv!value
)
)
)
)
}
)
},
buttons: a!buttonLayout(
primaryButtons: {
a!buttonWidget(
label: "Submit",
submit: true,
style: "PRIMARY"
)
}
)
)
)
}