How to get rid of formit + AjaxForm modx spam?

Question

MODX

<div class="main-form">
  <div class="main-form__container container">
    <div class="main-form__row row">
      <div class="main-form__col col-12 col-lg-9">
        <h2 class="main-form__title">Оставьте свои данные,<br>мы расчитаем стоимость и перезвоним вам.
        </h2>
      </div>
    </div>
    <form name="2-main" action="" class="main-form__form ajax_form af_example">
      <div class="main-form__row-form row"> 
        <div class="main-form__col col-12 col-lg-4 col-xl-3">
          <label class="main-form__label"> <span> Контактное лицо</span>
            <input class="main-form__input" name="name" type="text" placeholder="Введите имя"/>
          </label>
        </div>
        <div class="main-form__col col-12 col-lg-4 col-xl-3">
          <label class="main-form__label"> <span> Контактный телефон</span>
            <input class="main-form__input" name="phone" type="tel" placeholder="Введите телефон"/>
          </label>
        </div>
        <div class="main-form__col col-12 col-lg-4 col-xl-3">
          <label class="main-form__label"> <span> E-mail</span>
            <input class="main-form__input" name="email" type="email" placeholder="Введите email"/>
          </label>
        </div>
      </div>
      <div class="main-form__row-form row"> 
        <div class="main-form__col col-12 col-lg-4 col-xl-3">
          <label class="main-form__label"> <span> Наименование компании</span>
            <input class="main-form__input" name="organization" type="text" placeholder="Введите наименование"/>
          </label>
        </div>
        <div class="main-form__col col-12 col-lg-8 col-xl-6">
          <label class="main-form__label"> <span> Ваше сообщение</span>
            <textarea class="main-form__input" name="message" type="text" placeholder="Введите текст"></textarea>
          </label>
        </div>
      </div>
      
      <div class="main-form__row-form row align-items-center">
        <div class="main-form__col col-12 col-lg-5">
          <div class="main-form__agree-konf">
             Нажимая кнопку “Отправить заявку”, вы соглашаетесь с настоящей <a href="/legal.html">политикой конфиденциальности</a>
          </div>
        </div>
        <div class="main-form__col col-12 col-lg-7 col-xl-4 d-flex align-items-end justify-content-end">
          <button class="main-form__btn-show btn btn btn--transparent" type="button">Расширенная форма
          </button>
          <button class="main-form__btn-submit btn" type="submit">Отправить
          </button>
        </div>
      </div>
      
      
    </form>
  </div>
</div>

Answer 1

Usually Formit has one or a combination of several options:
1. Google Recaptcha V2
2. Math hook
3. Spam hook (checking if the hidden field is empty)
4. Checking against spam databases
Several useful links:
One
Two
Three
Four
It is also indirectly useful to send mail via smtp, have MX records on your domain, correctly configure SPF and DKIM server headers.