WordPress + Contact Form 7: Forms are not submitted, but test SMTP is submitted and access from less secure applications is enabled

Edit @Dianne: The solution was to change the SMTP plugin I was using to Postman SMTP. Thanks to @A.Cedano for the answer :) With that and a normal form text the problem was fixed.

I have a problem with a page that I am developing on my WordPress localhost (the theme I use is Rosa, this is its address: Theme ) and the form is not sent (I am using contact form 7). As something similar happened to me before, the first thing I did was make sure that the form was written correctly. Everything was fine and just in case it was something from there, to discard it I copied and pasted from another page that I made with the same plugin, the form and the header and body of the message. I have made sure that all the fields are correctly written, making the comparison (but with the data of my e-mail).

Once I made sure that everything was fine, as it still didn't work, I installed the plugin: WP Email SMTP and configured it to allow SMTP. I did the test and I received, in my Gmail e-mail, the test mail without any problem (so it is ruled out that the SMTP configuration is wrong).

Finally, I remembered a problem I had a few months ago with Gmail accounts and that gave me the same error (I asked about it here) so I went to the security section of Google accounts and made sure to have activated in the area of security the access of less secure applications.

All of the above is done correctly, but every time I try to fill in the form data and send it (with each and every one of the fields duly completed) I get the error. I have tried to fill in the form after doing control+f5 in case it was a cache problem and the same with an incognito browser, but the same error continues.

I've looked on the internet but I haven't found solutions (they all referred to SMTP and some to google account security, and I had already done those steps) and in this same forum. The closest thing I have found has been a question about a similar error in Laravel, but it has not clarified anything for me (although they were not using what I am using either).

Does anyone know why I keep getting the error? Here is an image of the error:

UPDATE:

With WP_DEBUG enabled, I looked at the Google Chrome console to see what errors might be coming up. These are the ones he told me (although two are from the Google map because I haven't configured it yet, but that shouldn't affect the form since they are separate).

On line 465 there is the following (it marks a warning in createShadowRoot() ) :

shadow = document.documentElement.createShadowRoot();

And the context of that line of code is as follows:

var propertyFilters = new CSSPropertyFilters(window, getPropertyFilters,
                                           addElemHideSelectors);

  // Use Shadow DOM if available to don't mess with web pages that rely on
  // the order of their own <style> tags (#309).
  //
  // However, creating a shadow root breaks running CSS transitions. So we
  // have to create the shadow root before transistions might start (#452).
  //
  // Also, using shadow DOM causes issues on some Google websites,
  // including Google Docs, Gmail and Blogger (#1770, #2602, #2687).
  if ("createShadowRoot" in document.documentElement &&
  !/\.(?:google|blogger)\.com$/.test(document.domain))
  {
shadow = document.documentElement.createShadowRoot();
shadow.appendChild(document.createElement("shadow"));

// Stop the website from messing with our shadowRoot
if ("shadowRoot" in Element.prototype)
{
  runInDocument(document, function()
  {
    var ourShadowRoot = document.documentElement.shadowRoot;
    var desc = Object.getOwnPropertyDescriptor(Element.prototype, "shadowRoot");
    var shadowRoot = Function.prototype.call.bind(desc.get);

    Object.defineProperty(Element.prototype, "shadowRoot", {
      configurable: true, enumerable: true, get: function()
      {
        var shadow = shadowRoot(this);
        return shadow == ourShadowRoot ? null : shadow;
      }
    });
  }, null);
}
  }

If I click on the link that the warning takes me to, it takes me to the following link: Chromestatus . I assume that everyone will be able to see it. However, as much as I read what appears on that page, I can't understand it well (my English isn't exactly very good).