建一页面eimg.aspx：
page_load内:
string emailstr = Request.QueryString["email"];
System.Drawing.Bitmap image = new System.Drawing.Bitmap(50, 18);//图片宽高,根据邮箱地址长高设
        Graphics g = Graphics.FromImage(image);

        try
        {
            //清空图片背景色
            g.Clear(Color.White);

            Font font = new System.Drawing.Font("宋体", 10, FontStyle.Regular);
            System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.FromArgb(0x78FE8A3F), Color.FromArgb(0x78FE8A3F), 1.2f, true);
            g.DrawString(emailstr, font, brush, 5, 2);


            //画图片的边框线
            g.DrawRectangle(new Pen(Color.FromArgb(0x78FE6903)), 0, 0, image.Width - 1, image.Height - 1);

            System.IO.MemoryStream ms = new System.IO.MemoryStream();
            image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
            Response.ClearContent();
            Response.ContentType = "image/Gif";
            Response.BinaryWrite(ms.ToArray());
        }
        finally
        {
            g.Dispose();
            image.Dispose();
        }


调用：
<img src="eimg.aspx?email=...">

------解决方案--------------------

C# code

            System.IO.MemoryStream ms = new System.IO.MemoryStream();
            image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
            Response.ClearContent();
            Response.ContentType = "image/Gif";
            Response.BinaryWrite(ms.ToArray());
不要了







=============> image.Save("filepath..");//保存到文件