Phosphorus and Lime

Read recent entry on the step-up in spam attacks -- not encouraging. I'm getting to work on a comment system for a php-based project I'm working on -- nothing extraordinary -- and have been exploring spam-filtering options.

One idea I'm considering: a two-button radio group at bottom of comment form by which user chooses either a captcha (default option) or an email message to validate the comment. If the commentor chooses email, the message is still posted, but say only for a short time -- say 2 hours -- before it is suppressed if the user has not validated it by clicking a URL link in email message. Simply an adaptation of the old user signup rigamarole but seems it might perhaps offer an extra layer of protection on top of other filtering techniques.

Or has this system itself been broken? Curious to have your opinion.

And kudos on your great work.

Thanks,
Tom