Many of you who run websites or blogs will know what a scourge auto form submitters are. In the past we’ve mainly found the problem to revolve around blog comment spam, but we soon fixed this with a solid captcha. 

In the last few weeks however, this has extended to the “contact us” form on our website. The situation has got really bad, I’ve received about 20 of these spam submissions in the last 24 hours alone and these bots are good enough to get around our server side form validation.

My biggest concern about implementing a captcha to fix this is that it might affect the conversion rate on the form. Whilst I can’t find any research to support this, my gut tells me that it will have some effect even if it is only slight. And who knows, the one that doesn’t convert may be the best lead of all…!

Does anyone have any advice around this?