Captcha

You can use Google Captcha for free for your mail form or where you need it.
Before Google did a good captcha, but now it has become generally super.
If before you had to enter the proposed text into the form, which was not just a random set of symbols, but similar to a word or a real word, then now there is NOT ANYTHING TO INTRODUCE.
Has come, I saw, I clicked and all!
How do they find out that this is a person? I do not think that we will understand until the end, and do not. The main thing is that it is convenient for the visitor and us.