How to add calculation captcha?

I have a website and getting 1000s of emails from website form. All the forms are just with random content. I have added a javascript to all the fields to make sure all the fields are filled and they are just placing random contents in the fields.

In wordpress website automatic captcha is installed but as this is the html website I have added text captcha with letters which was sending spam leads again and was not able to block the spam emails. Than I tried adding image captcha but got response from clients that its very difficult for them. I am thinking of using numeric captcha like addition or subtraction questions.

Any other way of stopping spam or let me know steps for adding calculation captcha.

[FONT=Verdana]Hi Donald, and welcome to the forums. :slight_smile:

I suggest you do a quick search here, because we’ve had a number of threads discussing various forms of captcha (and alternatives); you might well find something that fits your requirements.

Some suggested threads to start with:

http://www.sitepoint.com/forums/showthread.php?993779-Adding-Captcha-to-a-preexisting-Contact-Form[/FONT]

above links posted by technobear will help u for sure

You can add a captcha to your form to protect the spam emails from coming.

this needs a server side and eye verification at the same time.

there are 4-5 ways of adding captcha

if you want to make it very strict than you can make it like a question

count the number of words in this question and multiply it by 12.

but this may be very difficult for normal user as multiplying and counting can take some time as well as they may navigate away from your website

2nd way is to have alphabetical letters in text format but again robots can copy and paste it and submit it in the field and pass the javascript.

3rd way is to have an image based captcha with random letters but in that case you need a sound version too as some users may face problem with that kind of captcha. some users face hard time to read such letters and i have many friends who are trying to avoid such captcha.

best way is to put the plus and minus or logical captcha

you can do this by adding a php code to the form you are using and a javascript to check if the answer entered is right or wrong

server side validation is used in this code.

doing a quick search on google gave me this as a best result

If you follow above tutorial with video i think you should have it working. it is little bit technical and may take some time but if you copy and paste the code i think it should be working.

What CMS is in use for the website concerned?