To get rid of spam

On the website there is a form, the data which is sent in the mail. Until recently, the form filled with real people and in the mail came a live application (not spam). Somehow, the form (probably) got into the spam lists of spammers and the mail began to come plentifully spam. Bots or used for other purposes by spammers, is unknown.

The task is to get rid of (to redo, to optimize the shape of) the opportunity to use this form to spammers or software to make the bots not been able to fill it.

Diafan CMS