Sending SMTP e-mail with curl/php

curl-smtp.php

<?php
function read_cb($ch, $fp, $length) {
    return fread($fp, $length);
}

$fp = fopen('php://memory', 'r+');
$string = "From: <[email protected]>\r\n";
$string .= "To: <[email protected]>\r\n";
$string .= "Date: " . date('r') . "\r\n";
$string .= "Subject: Test\r\n";
$string .= "\r\n";
$string .= "Deneme mesaji\r\n";
$string .= "\r\n";
fwrite($fp, $string);
rewind($fp);

$ch = curl_init();
curl_setopt_array($ch, [
    CURLOPT_URL => 'smtps://smtp.example.com:465/example.com',
    CURLOPT_MAIL_FROM => '<[email protected]>',
    CURLOPT_MAIL_RCPT => ['<[email protected]>'],
    CURLOPT_USERNAME => 'username',
    CURLOPT_PASSWORD => 'password',
    CURLOPT_USE_SSL => CURLUSESSL_ALL,
    CURLOPT_READFUNCTION => 'read_cb',
    CURLOPT_INFILE => $fp,
    CURLOPT_UPLOAD => true,
    CURLOPT_VERBOSE => true,
]);

$x = curl_exec($ch);

if ($x === false) {
    echo curl_errno($ch) . ' = ' . curl_strerror(curl_errno($ch)) . PHP_EOL;
}

curl_close($ch);
fclose($fp);

I am sorry, but the example using curl/php given at first don't work for me:
First, I had to replace fopen('php://memory', 'r+') by fopen('php://temp', 'r+') otherwise I get "Warning: curl_setopt_array(): Cannot represent a stream of type MEMORY as a STDIO FILE* in ...",
and second, I get the error "35 = SSL connect error".
It is not a php/curl version problem, because it is recent (8.4.0) and my web server is written in PHP 8.3 on apache 2.4 under Windows 10 on my local PC machine.
It is not a configuration problem, because when I send the mail with an application written in C langage using libcurl's curl_easy_*() fonctions with the same options, with the same SMTP server (port 467 or 587) , on the same Windows 10 PC machine that works....
At this time, I have not solved the problem, any idea ?

Hello, it was written when PHP version 8 was not exist. Some parts may need to be updated.

For the SSL problem, it may be related to SSL/TLS version. (CURLOPT_SSLVERSION option).

Have you tried with using "smtp://" instead of "smtps://" schema? (start with plain text connection and upgrade to TLS - with CURLOPT_USE_SSL set to CURLUSESSL_ALL)