Description:
------------
Forcing an SMTP encryption channel to either SSLv2 or SSLv3 doesn't work as expected. When creating a network trace with Wireshark, it appears the stream is utilizing TLS1.0 instead.

Google's SMTP servers return a false positive result when forcing SSLv2 and SSLv3, as Google supports TLS1.0 and up.

When testing with Microsoft's 365 SMTP servers, a correct result is given as Microsoft only supports TLS1.2.


Verified with OpenSSL 1.1.1h and the following command:
openssl s_client -connect aspmx.l.google.com:25 -starttls smtp -servername mail.domain.com -no_tls1 -no_tls1_1 -no_tls1_2 -no_tls1_3

OpenSSL fails as expected.

Test script:
---------------
$SMTPconn = fsockopen("aspmx.l.google.com", 25, $error_int, $error_string, 10);
fwrite($SMTPconn, "EHLO " . "tls.php.net" . "\r\n");
while (!feof($SMTPconn)) {
	$line = fgets($SMTPconn);
	$read = array($SMTPconn); $write = null; $except = null; $timeout = 0; $utimeout = 200000;
	if (!stream_select($read, $write, $except, $timeout, $utimeout)) break;
}
fwrite($SMTPconn, "STARTTLS" . "\r\n");
while (!feof($SMTPconn)) {
	$line = fgets($SMTPconn);
	$read = array($SMTPconn); $write = null; $except = null; $timeout = 0; $utimeout = 200000;
	if (!stream_select($read, $write, $except, $timeout, $utimeout)) break;
}
stream_context_set_option($SMTPconn, 'ssl', 'verify_peer', false);
stream_context_set_option($SMTPconn, 'ssl', 'verify_peer_name', false);
stream_context_set_option($SMTPconn, 'ssl', 'allow_self_signed', true);
stream_context_set_option($SMTPconn, 'ssl', 'capture_peer_cert', true);
stream_context_set_option($SMTPconn, 'ssl', 'capture_peer_cert_chain', true);
$res = @stream_socket_enable_crypto($SMTPconn, true, STREAM_CRYPTO_METHOD_SSLv2_CLIENT);
var_dump($res);

Expected result:
----------------
int(0) or bool(false)

The connection should fail, as SSLv2 or SSLv3 are not supported.


Actual result:
--------------
bool(true)

The connection (falsely) succeeds by utilizing TLS1.0 instead of SSLv2 or SSLv3.