Hi,
I tried with your provided solution but failed to update record in database and send email automatically on session expire/end or logout.
 
 Protected Sub SignInButton_Click(sender As Object, e As EventArgs) Handles SignInButton.Click
        Dim mySelection = "select * from RegisteredCustomers where EmailAddress='" & EmailAddress.Text & "' and Passwords='" & Passwords.Text & "'"
        Dim adp As New OleDbDataAdapter(mySelection, cn1)
        Dim dt As New DataTable
        adp.Fill(dt)
        If dt.Rows.Count <> 0 Then
            EmailAddress1.Text = (dt.Rows(0).Item("EmailAddress"))
            Session("EmailAddress") = EmailAddress1.Text
            Session("EmailAddressforEmail") = EmailAddress1.Text
        End If
    End Sub
 
Protected Sub LogoutButton_Click(sender As Object, e As EventArgs) Handles LogoutButton.Click
        Session.Clear()
        Session.Abandon()
        Session.Remove("EmailAddress")
        'Session.RemoveAll()
        Response.Redirect("Home")
    End Sub
 Global.asax
 Sub Session_End(ByVal sender As Object, ByVal e As EventArgs)
        Dim val As [String] = Session("EmailAddressforEmail").ToString()
        cn1.Open()
        Dim cmd As New OleDb.OleDbCommand("Update RegisteredCustomersLog set LogoutDate = '" & Now.ToLongDateString & "', LogoutTime = '" & Now.ToLongTimeString & "' where EmailAddress = '" & val & "' ", cn1)
        cmd.ExecuteNonQuery()
        cn1.Close()
        SendHTMLMail()
        Session.Clear()
        Session.Abandon()
        Session.RemoveAll()
        Session.Remove("EmailAddress")
        Session.Remove("EmailAddressforEmail")
    End Sub