Generating email address images to avoid spam on your site

Nowadays, you can't publish an email address anywhere without receiving a bunch of spam immediately after. Those spam web crawlers just search in every site looking for everything and anything that resembles an email address.

I very often see people use different variations of writing their email like "myname at mydomain.com" or "myname at mydomain dot com".
I don't think this covers it anymore...
The best way, in my opinion, is to create an image of the email address instead of writing it. (That's what Facebook does as well.)

I started working on a user based site, and the users' emails will be displayed throughout the site. So I created a class that will dynamically generate email address images for me so my precious users won't be so vulnerable to all the spam out there.

Here it is:

// Members //
private int _emailFontSize = 8;
private string _emailFontFamily = "Verdana";
private Brush _emailBackgroundColor = Brushes.White;
private Brush _emailFontColor = Brushes.Navy;
 
// Properties //
// I cut this out, just for convenience //
 
// Methods //
public void CreateEmailImage(string email)
{
      // create the font object
      Font myFont = new Font(_emailFontFamily, _emailFontSize);
             
      // create the image object
      Bitmap emailImage = new Bitmap((int)(myFont.SizeInPoints * email.Length), 
			myFont.Height);
 
      Graphics imgGraphics = Graphics.FromImage((Image)emailImage);
      imgGraphics.FillRectangle(_emailBackgroundColor, 
		new Rectangle(new Point(0, 0), emailImage.Size));
      imgGraphics.DrawString(email, myFont, _emailFontColor, new PointF(0, 0));
             
      // measure the actual size of the email string
      SizeF stringSize = imgGraphics.MeasureString(email, myFont);
             
      // crop the image we created
      Bitmap finalImage = CropImage(emailImage, 
		new Rectangle(new Point(0, 0), new Size((int)stringSize.Width,
                                    (int)stringSize.Height)));
 
      // save the image to a local file
      finalImage.Save(email + ".gif", ImageFormat.Gif);
  }
 
  private Bitmap CropImage(Image imgCrop, Rectangle cropArea)
  {
      Bitmap bmpImage = new Bitmap(cropArea.Width, cropArea.Height - 1);
      Graphics bmpG = Graphics.FromImage(bmpImage);
      bmpG.DrawImage(imgCrop, new Point(0, 0));
      return bmpImage;
  }
} 

I will probably make some changes before using this on my site:

1. I don't think it's smart to give the file the name of the actual email address. I'll probably generate some unique ID but built from the users name.
2. I haven't decided yet if I want the image to be a link to contact the user. If so, then I must create a unique id for each user, and have the link lead to that page with the unique id so I can identify the user being contacted.
3. I'll probably add a simple caching mechanism to this, hence create a folder to store all the images, and then check if it exists before creating a new one each time.

Enjoy! :)