Thank you for your useful reply,
maybe the error showed by the try to send email by SMTP PHP was:
Warning: stream_socket_enable_crypto(): SSL operation failed with code 1.
OpenSSL Error messages: error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed
At the moment I will have issue on testing again this because I already setup my server… maybe I will see if I can remove Comodo and reinstall Let’s Encrypt than test again; if I can I will post here the results.
Thanks