通过 Mailgun API 作为 MIME 发送，没有 Mailgun 库

Question

I'm using PHPMailer to build an e-mail as a MIME string, and I want to send it via the Mailgun API, using curl to connect to the /v3/[mydomain]/messages.mime endpoint.

Mailgun documentation says the MIME string has to be sent as the message parameter, and that you must use multipart/form-data to send it as a file upload.

libcurl documentation says that if you give an array to the CURLOPT_POSTFIELDS option, the Content-type will be set as multipart/form-data .

I tried this:

curl_setopt($ch, CURLOPT_POSTFIELDS, ["message" => $mimeData]);

But the Mailgun API answers as follows:

{ "message": "'message' parameter is not a file" }

Answer 1

I managed to get it working by first creating a temporary file:

$mimeFile = tmpfile();
fwrite($mimeFile, $mimeData);

And passing it to a CURLFile:

$mime = new \CURLFile(stream_get_meta_data($mimeFile)['uri']);

After this, I got a new error message, 'to' parameter is missing , so I finally had to get the recipient addresses from PHPMailer (they are already in the MIME string, but the API doesn't seem to realize it):

curl_setopt($ch, CURLOPT_POSTFIELDS, [
    "to" => implode(", ", array_keys($this->getAllRecipientAddresses())),
    "message" => $mime
]);