Maybe:

Sub nur25444()

Sheets(1).Columns("A:A").Copy Sheets(2).Range("B1")
LastRow = Sheets(2).Range("B" & Rows.Count).End(xlUp).Row
Sheets(2).Range("A1").Formula = "=IF(ISNUMBER(SEARCH(""@"",B1)),RIGHT(B1,5),B1)"
Sheets(2).Range("A2").Resize(LastRow).Formula = "=IF(ISNUMBER(SEARCH(""@"",B2)),RIGHT(B2,5),A1)"
Sheets(2).Range("A1:A50000").Value = Sheets(2).Range("A1:A50000").Value
Sheets(2).Columns("B:B").TextToColumns Destination:=Range("B1"), DataType:=xlFixedWidth, _
        FieldInfo:=Array(Array(0, 1), Array(17, 1), Array(35, 1)), TrailingMinusNumbers _
        :=True

Sheets(2).Activate
For Each vCell In Range("B1:B" & Cells(Rows.Count, "B").End(xlUp).Row).Cells
If vCell = "" Then
Range(vCell.Address).Value = Range(vCell.Address).Offset(-1).Value
End If
Next vCell


End Sub