The Contact Form 7 plugin does not work

I set everything up as shown in the documentation/communities/videos, but when I try to submit the form, I get this: "An error occurred while sending the message. Please try again later. " Later, I tried to take the same template as in my other site, but this did not help, and I also tried to turn off the other plugins, but it did not help. How can I solve this problem? Or suggest another plugin with a free option to add a field for phone number.(yes, there are only two fields in the form - number and name.

Author: yourBadApple, 2021-02-13