Laravel Version

10.48.12

PHP Version

8.3.6

Database Driver & Version

No response

Description

config/mail.php

'failover' => [
'transport' => 'failover',
'mailers' => [
'mailgun',
'ses',
],
],

the rest is email source

normal email will got
Content-Type: multipart/related; boundary=xxx

broken email will got
Content-Type: multipart/mixed; boundary=xxx

normal email image path is
cid:d3a788f4cbf3a6aab32dcacde69a2e34@symfony

and the email raw about attachment
Content-ID: d3a788f4cbf3a6aab32dcacde69a2e34@symfony
Content-Type: image/png; name="d3a788f4cbf3a6aab32dcacde69a2e34@symfony"
Content-Transfer-Encoding: base64
Content-Disposition: inline;
name="d3a788f4cbf3a6aab32dcacde69a2e34@symfony"; filename=V9J4rKBvmB

broken email will got path is
cid:L7HALxfBwi

and the email raw about attachment
Content-ID: 2eabc9240b3557c72ad65e92a60f7f57@symfony
Content-Type: image/png; name="2eabc9240b3557c72ad65e92a60f7f57@symfony"
Content-Transfer-Encoding: base64
Content-Disposition: inline;
name="2eabc9240b3557c72ad65e92a60f7f57@symfony"; filename=L7HALxfBwi

Steps To Reproduce

send mail with mailable with view of html (blade)

when i change this path code with deep copy it's worked

path: vendor/symfony/mailer/Transport/RoundRobinTransport.php

`
public function send(RawMessage $message, ?Envelope $envelope = null): ?SentMessage
{
$exception = null;

while ($transport = $this->getNextTransport()) {
    try {
        $currentMessage = deep_copy($message); //here 
        return $transport->send($currentMessage, Envelope::create($currentMessage)); //here 
    } catch (TransportExceptionInterface $e) {
        $exception ??= new TransportException('All transports failed.');
        $exception->appendDebug(sprintf("Transport \"%s\": %s\n", $transport, $e->getDebug()));
        $this->deadTransports[$transport] = microtime(true);
    }
}

throw $exception ?? new TransportException('No transports found.');

}`
that may the mailgun modify the $message attchement property, and inface the symfony use clone but not deep copy