[RC5] spam

Ben Li banjili at bigfoot.com
Sun Jun 20 21:03:48 EDT 1999

At 18:28 9906.19 +0000, you wrote:
>Denie Andriessen said:
>It would still be rather easy actually, although admittedly it would be 
>more work for the spammer.  Once you know the font being used and have 
>a sample of every character in that font (easy) it would not be hard to 
>write a program to compare blocks of pixels with those which are 
>already known and to reconstruct the email addresses.
>It's just about the simplest form of image recognition.

I don't think that that is a really big concern since that would require
quite a bit of work from a spammer, just to get a maximum of ~100,000 email
addresses.  One GIF for each character sounds good since it prevents easy
harvesting from pages but the number of HTTP requests (neglecting local
agent caching) would increase very dramatically due to the need to fetch a
file for each character in each address displayed.  A simpler way of
preventing much of the harvesting would be to send the addresses as HTML
ampersand codes, like @, which will render as an address when viewed as
a human but will not show up as addresses when read as a file.  Any browser
worth using will support the use of such codes (including lynx).  This
solution, however, would increase the average page size in exchange for an
increase in the number of server hits as above.  Randomly embedding ASCII
000 in addresses may also work since browsers generally do not render nulls
whereas harvesting programs may treat them as something to be parsed :-)  



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