How can I send email to each user separately listed in gridview by clicking on mail button?

**Currently whole grid is sending to all users. I want to send email to each user separately and only their data should be email to them.**
**home aspx. page**
<asp:Button ID="mail" runat="server" Text="Mail" CssClass="button" OnClick="mail_Click" Style="margin-left: 10px; width: 100px; font-family: Verdana, Geneva, sans-serif;" />
<asp:GridView ID="grdTask" CssClass="gridAdmin" runat="server" HeaderStyle-BackColor="LightSlateGray" EnableViewState="true" EmptyDataText="No Record Found!" BorderStyle="Groove" RowStyle-BackColor="LavenderBlush" AlternatingRowStyle-BackColor="Lavender" AutoGenerateColumns="false" HeaderStyle-ForeColor="White" RowStyle-ForeColor="Black" Width="100%" CellPadding="4" OnRowData ...