I installed Contact form 7 in my wordpress blog and there are several spam messages coming through it. Then I added really simple captcha/ recaptcha for the form. But still the spam messages are getting submitted.
How can I block this? Please help me.
Thanks in advance.
There are a lot of papers and works related to spam blocking. For example, you can ask easy questions, like 2+7 instead of captcha but i dont know how powerful is that now, because spammers are also improving themselves.
You can also block by looking at their behaviour, for example, spambot enters to your website, and after one-two second it sends its spam to your website, this is not human behaviour, so dont allow that post.
You can search on google about that and I’m sure you can find a lot of stuff related to it
As I said, there is a lot of research going on in this issue, you can use google scholars too
Also this question looks similar to your question.
You can try to use the honeypot plugin: http://wordpress.org/extend/plugins/contact-form-7-honeypot/ (Note: I haven’t tested it, but I use a similar functionality in Gravity Forms, and it works great!).
Make sure to activate the Akismet plugin. It will help capture a good deal of the spam that gets through your forms.
I would also advice to use at least a combination of Captcha and Akismet like Bill already mentioned. You can find a very good tutorial on this topic at http://cool-tricks.net/contact-form-7-configuration/