[boost] What is trac doing and how do I stop it doing it??

I am attempting to update a ticket and I am getting this: ------------------ Captcha Error Submission rejected as potential spam (Content contained 1 blacklisted patterns) Trac thinks your submission might be Spam. To prove otherwise please provide a response to the following. ------------------- I would not mind but there is nothing to respond to and what I have typed seems to be lost. Where is there guidance on how to avoid this problem, please? John