Twilio功能-彩信到电子邮件-附件显示为空白

Question

我编写了一个Twilio函数，以使用Sendgrid api将传入的MMS消息发送到电子邮件。

mediaurl中的图像作为电子邮件的附件发送。

已正确接收电子邮件。但是附件显示空白图像。

下面是用于发送电子邮件的代码。如果我使用静态网址（https://demo.twilio.com/owl.png）而不是MediaUrl0，附件将正确显示。

  https.get(event.MediaUrl0, (resp) => {
        resp.setEncoding('base64');

        let data = '';

        // A chunk of data has been recieved.
        resp.on('data', (chunk) => {
            data += chunk;
        });

        // The whole response has been received. 
        resp.on('end', () => {

            body = body + "\n\nImage: " + event.MediaUrl0;

            const contentType = event.MediaContentType0;

            let acontentType = contentType.split("/");
            let filename = event.MessageSid + "." + acontentType[1];

            request = {
            method: 'POST',
            url: '/v3/mail/send',
            body: {
            personalizations: [{
            to: [{ email }]
            }],
            from: {
              email: `${from}@${domain}`
            },
            subject: `RE: ${from}`,
            content: [{
                type: 'text/plain', value: body
            }],
            attachments: [
                {
                content: data,
                filename: filename,
                type: contentType,
                disposition: 'attachment'
                },
            ],
            }
            };

            sendgrid
            .request(request) // send the email
            .then(() => done(null, new Twilio.twiml.MessagingResponse())) // send TwiML output
            .catch(done); // quiet failure 

        });

    }).on("error", (err) => { // if can not read, send sms


    });