Hi! My name is Eugene, I'd recommend to use one of the following methods: create some hidden field, ususaly spam bots does not recognize if field is hidden, so we check this field is not empty, consider it is spam. The next one is checking cookies, spam bot does not use it, and the third one - spam bots does not run js, we can run some code in external file and check if it runs form is valid, if not it is bot. Contact me and we will discuss it. Thank you.