Macro send notification when release date is not valid anymore - excel

Question

Next is some macro which compare cell D with current date and if it is in past it send notification to email defined in cell L. The problem here is that the macro need to be run manually by pressing Alt+F8, so the question is how to make the macro automatically run when it noticed that updated cell D value is in past, so there is no need all the time to run the macro manually.
Thanks in advance
Sub SendMail()
Dim OutApp As Object
Dim OutMail As Object
Dim RelDate As Range
Dim lastRow As Long
Dim dateCell, dateCell1 As Date
Application.ScreenUpdating = False
Set OutApp = CreateObject("Outlook.Application")
OutApp.Session.Logon
lastRow = Range("A" & Rows.Count).End(xlUp).Row
On Error GoTo cleanup
For Each RelDate In Range("D2:D" & lastRow)
If RelDate = "" Then GoTo 1
dateCell = RelDate.Value
dateCell1 = Cells(RelDate.Row, "C").Value
If dateCell < Date Then ' this if cell value is smalle than today then it will send notification
Set OutMail = OutApp.CreateItem(0)
On Error Resume Next
With OutMail
.To = Cells(RelDate.Row, "L").Value
.Subject = "Release Date Changed" ' Change your massage subject here
'Change body of the massage here
.Body = "Dear " & Cells(RelDate.Row, "E").Value _
& vbNewLine & vbNewLine & _
"The release date of " & Cells(RelDate.Row, "A").Value & _
" is changed to " & dateCell _
& vbNewLine & vbNewLine _
& vbNewLine & vbNewLine & _
"Regards," & vbNewLine & _
"Your Name"
.send
End With
On Error GoTo 0
Set OutMail = Nothing
End If
' Cells(RelDate.Row, "C").Value = dateCell
' RelDate.ClearContents
1: Next RelDate
cleanup:
Set OutApp = Nothing
Application.ScreenUpdating = True
End Sub

Answer 1

Use this code in worksheet_change event. It will compare the date in all the changed cells in column "D" and if condition is true, it will call the sendmail procedure. Please adjust your sendmail code accordingly.
This code also works if you copy paste multiple rows of data.
Hope that help!. :-)
Private Sub Worksheet_Change(ByVal Target As Range)
Dim to_email As String
Dim subject As String
Dim body As String
For Each cell In Target.Cells
On Error Resume Next
If cell.Column = 4 And cell < Date Then
On Error GoTo errhandler
to_email = ActiveSheet.Cells(cell.Row, "L").Value
subject = "Release Date Changed"
body = "Dear " & ActiveSheet.Cells(cell.Row, "E").Value _
& vbNewLine & vbNewLine & _
"The release date of " & ActiveSheet.Cells(cell.Row, "A").Value & _
" is changed to " & ActiveSheet.Cells(cell.Row, 4) _
& vbNewLine & vbNewLine _
& vbNewLine & vbNewLine & _
"Regards," & vbNewLine & _
"Your Name"
sendmail to_email, subject, body
End If
Next cell
Exit Sub
errhandler:
Err.Raise Err.Number, Err.Source, Err.Description
End Sub
Sub sendmail(to_email As String, subject As String, body As String)
adjust your code accordingly
End Sub