尽管作为 (text/csv) 发送的文件附件仍以 (text/plain) 形式发送

Question

因此，当发送带有 CSV 文件的 email 时，（ "symfony/mailer": "6.0.*" ）

我将其专门设置为text/csv ，但是当它通过网络传输并从 email 下载附件时，由于某种原因，文件的格式是text/plain ？

$attchment = "./CSV/00000-projectExport.csv";
$email = (new Email())
            ->to($address)
            ->from(Address::create('Project <project@example.com>'))
            ->attachFromPath($attachment, 'Project Export', 'text/csv')
            ->subject('Project Export')
            ->text("Hi, Please find attached a CSV with the data for {$projectName} from the app. Thanks. ")
            ->html("<p>Hi, Please find attached a CSV with the data for {$projectName}  from the app. Thanks. </p>");

        try {
            $mailer->send($email);
        } catch (TransportExceptionInterface $e) {
            // some error prevented the email sending; display an
            // error message or try to resend the message
            echo '#2' . $e->getMessage();
        }

为什么是这样。 有人有类似的问题吗？