In the night of Feb 10th, 1999, our chemical structure GIF image generator service (http://www2.chemie.uni-erlangen.de/services/gifcreator/) was under attack.
The (identified) host 188.8.131.52 posted several ten thousand image generation requests, which all failed, probably due to a programming error in the requester script. Some hours before that and again later a few requests from the same source were successfully processed, probably the result of manual experimental submission. This issue has now been resolved after we were able to contact the administrator of the offending host's network.
We do not appreciate this kind of exploitation. The conditions of this service explicitly forbid the use of the images for a commercial application, which given the number of requests looks likely. The images contain copyright information embedded in the image data. Even if the intended use was for a non-commercial purpose, we definitely prefer to be informed beforehand if such a massive number of structures is going to be processed. In such cases, send us an email. We are willing to help and process your structures as a batch job without going through the Web interface.