Java 如何通过google app engine发送带有CSV文件附件的gmail邮件

我正在尝试通过google app engine发送一封带有csv附件的电子邮件，收件人没有收到邮件。当我在Google App Engine中查看日志时，也没有报告任何错误。出了什么问题？有人能告诉我，是否有可能通过邮件发送csv文件作为附件使用谷歌应用程序引擎？如果是的话，你能告诉我怎么做吗

      Properties props = new Properties();
Session session = Session.getDefaultInstance(props, null);

try {
    Message msg = new MimeMessage(session);
    msg.setFrom(new InternetAddress("xxx@gmail.com"," Admin"));
         msg.addRecipient(Message.RecipientType.TO, new InternetAddress(emailto, "Mr. User"));
    msg.setSubject("Expence Tracker with Attachment");

    String htmlBody=msgbody;   

    byte[] attachmentData= attach.getBytes(); 
         Multipart mp = new MimeMultipart();

    MimeBodyPart htmlPart = new MimeBodyPart();
    htmlPart.setContent(htmlBody, "text/html");
    mp.addBodyPart(htmlPart);

    MimeBodyPart attachment = new MimeBodyPart();
    attachment.setFileName("myfile.csv");
    attachment.setContent(attachmentData, "text/comma-separated-values");
    mp.addBodyPart(attachment);

    msg.setContent(mp);

    //resp.getWriter().println("Mail  Details :To- "+emailto);

} catch (AddressException e) {

    resp.getWriter().println("Mail  Details :Error "+e);
} catch (MessagingException e) {
    resp.getWriter().println("Mail  Details :Error "+e);
}

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这是发送CSV附件的示例。CSV在blobstore中。 它在Python中使用GAE邮件和blobstore API。将其转换为Java并不困难

    blob_key = files.blobstore.get_blob_key(file_name)
    blob_info = blobstore.BlobInfo.get(blob_key)        
    blob_reader = blobstore.BlobReader(blob_key)                        
    message = mail.EmailMessage(sender = 'noreply@example.com, 
                                subject = 'CSV attached')        
    message.body = 'Download attached CSV'                       # only a text body
    message.attachments = [blob_info.filename,blob_reader.read()]
    message.send()  

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我看不到任何发送您创建的消息的方法，它是否在代码的另一部分？如果是，你也能分享吗？