使用Gmail API发送的邮件中缺少附件，但仅适用于收件人

Question

在JavaScript中调用Gmail API以发送带有HTML正文和约100KB PDF附件的邮件时，附件会正确显示为附加到发件人的Gmail Sent文件夹中的邮件，但不会显示在收件人的邮件上。

API调用是对以下对象的POST请求：

https://www.googleapis.com/upload/gmail/v1/users/me/messages/send?uploadType=media

发送到API的请求类似于以下内容：

{
"headers": {
"Authorization": "Bearer {auth_token}"
},
"method": "POST",
"contentType": "message/rfc822",
"contentLength": 134044,
"payload": "{see_below}",
}

请求主体为：

MIME-Version: 1.0
To: =?utf-8?B?TWlrZSBD?=<[e-mail]>
CC: =?utf-8?B?TWlrZSBD?=<[e-mail]>
BCC: =?utf-8?B??=<[e-mail]>
From: =?utf-8?B?TWlrZSBxWXsd2lr?=<[e-mail]>
Subject: =?utf-8?B?subjectLine-removedForThisPost?=
Content-Type: multipart/alternative; boundary=__boundary__
--__boundary__
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: base64
{base64_encoded_string}
--__boundary__
Content-Type: text/html; charset=UTF-8
Content-Transfer-Encoding: base64
{base64_encoded_string}
--__boundary__
Content-Type: application/pdf; name="File Name.pdf"
Content-Disposition: attachment; filename="File Name.pdf"
Content-Transfer-Encoding: base64
{base64_encoded_string}
--__boundary__--

注：Gmail API Uploading Attachments文档指出，当上传"附件"时需要CCD_ 2；简单的"；附件(5MB以下)。我这样做是为了让我的请求包括Content-Length，其中包含PDF附件总字节数的整数值。但是，我注意到Content-Length没有包含在有效载荷中。

我尝试将邮件的Content-Type从multipart/alternative更改为multipart/mixed，这样PDF附件就可以正确地附加到收件人的邮件上，但邮件的HTML正文呈现为纯文本(显示了HTML标记)，还有一个名为noname.html的附加附件，其中包括呈现为HTML的HTML内容。

我需要这样做，以便收件人邮件中的电子邮件既有HTML呈现的正文，也有PDF附件。

更新：我在这里上传了原始电子邮件的示例。发送的消息在左侧，接收的消息在右侧。

Answer 1

只需替换：

Content-Type: multipart/alternative; boundary=__boundary__

用于：

Content-Type: multipart/mixed; boundary=__boundary__

这是我用JS 编写的全部功能

函数createMimeMessage_(msg)｛

var nl="\n"；var border=">ctrlq_dot_org"；

var mimeBody=[

"MIME-Version: 1.0",
"To: "      + msg.to.email,//+ encode_(msg.to.name) + "<" + msg.to.email + ">",
"Cc: "      + msg.cc.email,
"Bcc: "      + msg.bcc.email,
"From: "    + msg.from.email,//+ encode_(msg.from.name) + "<" + msg.from.email + ">",
"Subject: " + encode_(msg.subject), // takes care of accented characters
"In-Reply-To: " + (msg.reply_to || ""),
"References: " + (msg.reply_to || ""),
"Content-Type: multipart/mixed; boundary=" + boundary + nl,
"--" + boundary,
// "Content-Type: text/plain; charset=UTF-8",
// "Content-Transfer-Encoding: 7bit",
// "Content-Disposition: inline" + nl,
// msg.body.text + nl,
// "--" + boundary,
"Content-Type: text/html; charset=UTF-8",
"Content-Transfer-Encoding: base64" + nl,
new Buffer(msg.body.text).toString('base64') + nl,

]；

对于(var i=0；i<msg.files.length；i++){

var attachment = [
"--" + boundary,
"Content-Type: " + msg.files[i].mimeType + '; name="' + msg.files[i].fileName + '"',
'Content-Disposition: attachment; filename="' + msg.files[i].fileName + '"',
"Content-Transfer-Encoding: base64" + nl,
msg.files[i].bytes
];
mimeBody.push(attachment.join(nl));

}

mimeBody.prush("--"+边界+"--")//console.log(mimeBody)；

return mimeBody.join(nl)；

}

Answer 2

您的问题有两部分：

1. 如何将附件传递给收件人
2. 如何包含HTML的附件和纯文本替代方案

Tiger开发人员(multipart/alternative至multipart/mixed)部分回答了这一问题。正如您所指出的，问题在于，简单地这样做会使您无法使用替代纯文本。这是因为您正在删除multipart/alternative，其特定角色是提供该替代方案。

你需要做的是创建第二个边界，然后将纯文本分组&HTML部分在一起。看看这个同样来自CTRLQ的例子，并注意到我包含的altBoundary。

function createMimeMessage_(msg) {
var nl = "n";
var boundary = "__ctrlq_dot_org__";
var altBoundary = "__alt_ctrlq_dot_org__";
var mimeBody = [
"MIME-Version: 1.0",
"To: "      + encode_(msg.to.name) + "<" + msg.to.email + ">",
"From: "    + encode_(msg.from.name) + "<" + msg.from.email + ">",
"Subject: " + encode_(msg.subject), // takes care of accented characters
"Content-Type: multipart/mixed; boundary=" + boundary + nl,
"--" + boundary,
"Content-Type: multipart/alternative; boundary=" + altBoundary + nl,
"--" + altBoundary,
"Content-Type: text/plain; charset=UTF-8",
"Content-Transfer-Encoding: base64" + nl,
Utilities.base64Encode(msg.body.text, Utilities.Charset.UTF_8) + nl,
"--" + altBoundary,
"Content-Type: text/html; charset=UTF-8",
"Content-Transfer-Encoding: base64" + nl,
Utilities.base64Encode(msg.body.html, Utilities.Charset.UTF_8) + nl,
"--" + altBoundary + "--"
];
for (var i = 0; i < msg.files.length; i++) {
var attachment = [
"--" + boundary,
"Content-Type: " + msg.files[i].mimeType + '; name="' + msg.files[i].fileName + '"',
'Content-Disposition: attachment; filename="' + msg.files[i].fileName + '"',
"Content-Transfer-Encoding: base64" + nl,
msg.files[i].bytes
];
mimeBody.push(attachment.join(nl));
}
mimeBody.push("--" + boundary + "--");
return mimeBody.join(nl);
}