how to send mail to reception mailid

protected void bt_submit_Click(object sender, EventArgs e)
  {
      if (string.IsNullOrEmpty(Request.QueryString["Pageid"]))
      {
          if (Session["Id"] != null)
          {

              string str1 = "insert into tbl_conversation([cust_ID],[rep_ID],[conversation_description],[conversation_datetime],[conversation_type],[callback_datetime],[conversation_status],Role) values('" + ddlcustomer.SelectedItem.Value + "','" + Convert.ToInt64(Session["Id"]) + "','" + txtdescriton.Text + "','" + DateTime.Parse(Request.Form[txtconversation_datetime.UniqueID]) + "','" + ddlconversationtype.SelectedItem.Value + "','" + txtcallback.Text + "','1','Admin')";



             // string str2 = "insert into tbl_conversation([cust_ID],[rep_ID],[conversation_description],[conversation_datetime],[conversation_type],[callback_datetime],[conversation_status],Role) values('" + ddlcustomer.SelectedItem.Value + "','" + Convert.ToInt64(Session["Id"]) + "','" + txtdescriton.Text + "','" + DateTime.Parse(Request.Form[txtconversation_datetime.UniqueID]) + "','" + ddlconversationtype.SelectedItem.Value + "','" + txtcallback.Text + "','1','Admin')";
            
             c1.exexuteQry(str1);



          }
          else
          {
              if (Session["RecId"] != null)
              {
                  string str1 = "insert into tbl_conversation([cust_ID],[rep_ID],[conversation_description],[conversation_datetime],[conversation_type],[callback_datetime],[conversation_status],Role) values('" + ddlcustomer.SelectedItem.Value + "','" + Convert.ToInt64(Session["RecId"]) + "','" + txtdescriton.Text + "','" + DateTime.Parse(Request.Form[txtconversation_datetime.UniqueID]) + "','" + ddlconversationtype.SelectedItem.Value + "','" + DateTime.Parse(Request.Form[txtcallback.UniqueID]) + "','1','User')";
                  c1.exexuteQry(str1);
              }
          }



          Response.Write(@"<script langauge='text/javascript'>alert('...Insert successfull...');</script>");
      }
      else
      {
          if (Session["Id"] != null)
          {
              string str = "update tbl_conversation  SET [cust_ID] ='" + ddlcustomer.SelectedItem.Value + "'  ,[rep_ID] ='" + Convert.ToInt64(Session["Id"]) + "'  ,[conversation_description] ='" + txtdescriton.Text + "' ,[conversation_datetime] ='" + DateTime.Parse(Request.Form[txtconversation_datetime.UniqueID]) + "' ,[conversation_type] = '" + ddlconversationtype.SelectedItem.Value + "',[callback_datetime] ='" + DateTime.Parse(Request.Form[txtcallback.UniqueID]) + "',Role='Admin'   where conversation_ID='" + Convert.ToInt64(Request.QueryString["Pageid"]) + "'  ";
              c1.exexuteQry(str);
          }
          else
          {
              if (Session["RecId"] != null)
              {
                  string str = "update tbl_conversation  SET [cust_ID] ='" + ddlcustomer.SelectedItem.Value + "'  ,[rep_ID] ='" + Convert.ToInt64(Session["RecId"]) + "'  ,[conversation_description] ='" + txtdescriton.Text + "' ,[conversation_datetime] ='" + DateTime.Parse(Request.Form[txtconversation_datetime.UniqueID]) + "' ,[conversation_type] = '" + ddlconversationtype.SelectedItem.Value + "',[callback_datetime] ='" + DateTime.Parse(Request.Form[txtcallback.UniqueID]) + "',Role='User'   where conversation_ID='" + Convert.ToInt64(Request.QueryString["Pageid"]) + "' ";
                  c1.exexuteQry(str);
              }
          }
          Response.Write(@"<script langauge='text/javascript'>alert('...Update successfull...');</script>");
          Response.Redirect("Cust_Conversation.aspx");

      }

      fillgrid();
      clear();

  }

<pre><pre lang="c#"><pre lang="c#">