Unfortunately, the basic form-to-email form included with Pages, Stage, and CRG doesn’t have any options for combating email spam. The option used to be to upgrade to Form-to-email’s Pro version. They used to sell this for $29.
With it you could enable Captcha (though I wasn’t able to get that to work on the first try and then lost interest) and turn on features that block messages containing gibberish words and links.
But the folks at Form-to-email have changed their pricing plans. Now to get the old Pro version features you have a couple of choices. The least expensive option is a $2.25/mo plan for one form. You might be able to integrate this with TTG because there’s an option in the plug-in to use Form-to-email remote. Matt’s not sure if the new cloud-based Form-to-email will be compatible with this. He addresses it here.
To get the old Pro version and install it in the TTG plug-ins, you now have to buy a Developer’s license, which is $129 for use on only one website and $199 if you’re running multiple sites. http://formtoemail.com/developer_pricing.php
Matt and Ben are planning on creating their own version of a form handling script for the CE4 plug-ins, but for now your options are to either live with the spam, spend some $$ on the Developer’s version, or take your chance on the subscription version and hope that it’s compatible with the form-to-email remote option in the TTG plug-ins.
As far as modifying the current form, I don’t have the php skills to tackle that one.
One other option I can think of is if you’re also using Theme for WordPress for a blog. With WordPress you can use the Akismet plug-in to greatly reduce spam on blog posts (activation is not free, but it’s not expensive either).
You can also use it on email forms in a WordPress page.
So if you’ve got a blog, you could create another page in WordPress and add a contact form to it. Then use this page and its contact form rather than the stock TTG contact page/form.
I’m using Contact Form 7 for this site and here’s a how-to on how to integrate Akismet into Contact Form 7: http://contactform7.com/spam-filtering-with-akismet/
