After removing CAPTCHAS from our software and replacing it with the method discussed in An alternative to irritating CAPTCHAs about 3 months ago, I went through our server log files to see how successful the method has been.

Luckily I made a log entry every time the software rejected a submission based on the belief that it came from a spambot, so it was relatively easy to obtain the following stats.
For the period 01-01-2007 to 23-02-2007 there has been approximately 7345 spam submissions that have been blocked by the software. That comes to an average of 136 spam submissions a day.

But the real question is how many time has it let spam through?
Well in the beginning there was the odd case here and there where a spambot came through but that was normally due to them having a cached version of the form and a simple change of the form's action resolved that problem. So all in all it has proven to be a successful weapon in the fight against spambots.

If, or should I rather say, when the time comes that the bots get past this form of prevention then there are always further steps that can be taken as I found out in an article by Ned Batchelder.

But until that day comes I'll sit back and enjoy our CAPTCHA-less forms and have a bit of a chuckle every time I see an entry in the server log saying "Form submission failed due to possible spam activity."