Creat Alert when date is between two dates

I'm trying to create a macro that will check column (D3:D1000) and send an alert upon opening the spreadsheet if any values falls between (=Today()+45) and (=Today()). I've gotten it to work with just checking D3, but not sure how to get it to loop through the other rows. I have cell A1 set to =Today()


Private Sub Workbook_Open()

If Range("A1") >= Range("D3") - 45 Then
response = MsgBox("Check NDA Date", , "Alert!")
End If



End Sub

Pl see attached file.Workbook_open event is used.

Thanks! That did the trick!