private void richTextMSG_TextChanged(object sender, EventArgs e)
        {
            compteur = richTextMSG.Text.Length;
            if (richTextMSG.Text.Length == 0)
                label6.Text = "message Length : 0";
            else
                label6.Text = "message Length : " + compteur;
        }

        private void btnRest_Click(object sender, EventArgs e)
        {
            this.txtFrom.Text="";
            this.txtMdp.Text = "";
            this.txtSubject.Text = "";
            this.txtTo.Text = "";
            this.richTextMSG.Text = "";
            label6.Text = "message Length : 0";
        }