What services are available for testing whether transactional emails are in spam?

Question

Software testing

Tell me, please, what are the services for testing if transactional emails get into spam on a variety of email services?
Those. so that they give a list of email addresses on different servers, I sent the same letter from the server to each address, for example, a registration letter, and I saw in the statistics how much came in, how many got into spam. There is such a service - emailstream.ru and what else is there?

Answer 1

General mail test - https://www.mail-tester.com/

Answer 2

There is such a service for checking letters for spam spamtester.bazaaremail.com
It analyzes quite well, gives a rating and problematic words.

Answer 3

Replace

$sql = "INSERT INTO catalog (title, author, pubyear,price) VALUES ('" . $title . "','" . $author . "','" . $pubyear . "','" . $price . "')";

on the

$sql = "INSERT INTO catalog (title, author, pubyear,price) VALUES (?,?,?,?)";