Sub Colonne_I()
Dim i As Integer
derligne = Range("A4").End(xlDown).Row
my_message = "Les Cellules Présentant des abscences sont: " & vbCrLf
For i = 4 To derligne
If Range("B" & i).Value <> "" And Range("I" & i).Value = "" Then
my_message = my_message & "I" & i & vbCrLf
End If
Next
MsgBox my_message
End Sub