public class Mail
{
    private string user = "xxx@gmail.com";
    private string password = "password";
    public void sendEmail(string strTo, string strSubject, string strBody)
    {
        MailMessage objMailMessage = new MailMessage();
        System.Net.NetworkCredential objSMTPUserInfo = new System.Net.NetworkCredential();
        SmtpClient objSmtpClient = new SmtpClient();

        objSmtpClient = new SmtpClient("smtp.web.de", 25);//port 25 or 587
        objSmtpClient.EnableSsl = true;
        objSmtpClient.Timeout = 10000;
        objSmtpClient.DeliveryMethod = SmtpDeliveryMethod.Network;
        objSmtpClient.UseDefaultCredentials = false;
        objSmtpClient.Credentials = new System.Net.NetworkCredential(user, password);

        objMailMessage.From = new MailAddress(user);
        objMailMessage.To.Add(new MailAddress(strTo));
        objMailMessage.Subject = strSubject;
        objMailMessage.Body = strBody;

        try
        {
            objSmtpClient.Send(objMailMessage);
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
        }

        finally
        {
            objMailMessage = null;
            objSMTPUserInfo = null;
            objSmtpClient = null;
        }
    }
}