using Outlook = Microsoft.Office.Interop.Outlook;
protected void SendEmailBtn_Click(object sender, EventArgs e)
        {
            Outlook.Application OutlookApp = new Outlook.Application();
            Outlook.MailItem mailItem = (Outlook.MailItem)OutlookApp.CreateItem(Outlook.OlItemType.olMailItem);
            mailItem.Subject = "Test Send Email";
            mailItem.BCC = "test@test.com";
            mailItem.Body = "Dear";
            mailItem.Display(false);
        }

<a href="mailto:?bcc=test@test.com&subject=Test+Send+Email&body=Dear">My Hyperlink</a>

System.Diagnostics.Process.Start("mailto:?bcc=test@test.com&subject=Test+Send+Email&body=Dear");