I'm using the GSuite OAuth2.0 Playground to test code to send emails through the Gmail API. I have successfully send plain emails and emails with just attachments. But when trying to send an email with both text and an attachment, I have hit a wall.
The following code, when tested in the Playground, successfully sends the message, and is received but the attachment is gone! When I click "Show Original" in the receiving Gmail account, it shows all of the header data and code, but nothing about the attachment. It's as if the Gmail server is stripping it out without giving any error messages. I am dumbfounded as to why.
Furthermore, when I look in the Sent folder of the sender's account, the email is there with the attachment! If I click "Show Original" from the sender's account, the attachment is NOT there. But I can easily see it when just looking at the email normally. And if I forward the email with the attachment, then it does successfully arrive with the email message. So it IS being stored in the sender's Sent folder, just for some reason not making it to the original recipient.
Here is what I am submitting in the OAuth Playground. I have edited the emails for privacy:
POST /upload/gmail/v1/users/me/messages/send?uploadType=multipart HTTP/1.1
Host: www.googleapis.com
Content-length: 7512
Content-type: message/rfc822
Authorization: Bearer ya29.Il_AB9XB2T68fKbhDZx37Y30qAUk89GfCzXwB8IQ1Asu4839djNUethOBPwya18TK6-aGD98TrlI_3woFe34NSZIKBPV2QH9_kim_tslZXVWh_NWHf6dHF2bsvEWPg8FTw
MIME-Version: 1.0
From: Mr. Sender <sender@gmail.com>
Subject: Test Attachment
To: receiver@gmail.com
Content-Type: multipart/alternative; boundary=000000000000b84ac3059fa3c6aa
--000000000000b84ac3059fa3c6aa
Content-Type: text/html; charset=UTF-8
<h1>Can you see this?</h1><br><br>Did it work?
--000000000000b84ac3059fa3c6aa
MIME-Version: 1.0
Content-Type: image/jpeg
Content-Disposition: attachment; filename="Page Divider - Marble.jpg"
Content-Transfer-Encoding: base64
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k60UUANXpQ3SiigDPuh81Zs/Q0UUAYV796l08DeKKKAOptxhBUN4Tg80UVDGZ8BPmDnvWuv+r/CiigBI/u1IKKKAEkAxUSdaKKALsYG2nYGelFFUhEiUPRRTArTfdNZE/wB+iigCxadKvN0oooAozE7+tEfJoooA0YAMdKsGiigBB9w1Ruu9FFAGY33qkjoooAH+9UiUUUAXIRVxKKKAJDUR60UUAPSpe1FFADWqFutFFACinUUUAKtPPSiigCtL1pI+tFFAErdKEPNFFAFqPpTzRRQBXnqoxOaKKALNv2q8OlFFACjpUT0UUAMFSCiigBrVC1FFAAtS0UUAOH3agk60UUANXpQ3SiigDPuh81Zs/Q0UUAYV796l08DeKKKAOptxhBUN4Tg80UVDGZ8BPmDnvWuv+r/CiigBI/u1IKKKAEkAxUSdaKKALsYG2nYGelFFUhEiUPRRTArTfdNZE/36KKALFp0q83SiigCjMTv60R8miigDRgAx0qwaKKAEH3DVG670UUAZjfeqSOiigAf71SJRRQBchFXEoooAkNRHrRRQA9Kl7UUUANaoW60UUAKKdRRQAq089KKKAK0vWkj60UUASt0oQ80UUAWo+lPNFFAFeeqjE5oooAs2/arw6UUUAKOlRPRRQAwVIKKKAGtULUUUAC1LRRQA4fdqCTrRRQA1elDdKKKAM+6HzVmz9DRRQBhXv3qXTwN4oooA6m3GEFQ3hODzRRUMZnwE+YOe9a6/6v8ACiigBI/u1IKKKAEkAxUSdaKKALsYG2nYGelFFUhEiUPRRTArTfdNZE/36KKALFp0q83SiigCjMTv60R8miigDRgAx0qwaKKAEH3DVG670UUAZjfeqSOiigAf71SJRRQBchFXEoooAkNRHrRRQA9Kl7UUUANaoW60UUAKKdRRQAq089KKKAK0vWkj60UUASt0oQ80UUAWo+lPNFFAFeeqjE5oooAs2/arw6UUUAKOlRPRRQAwVIKKKAGtULUUUAC1LRRQA4fdqCTrRRQA1elDdKKKAM+6HzVmz9DRRQBhXv3qXTwN4oooA6m3GEFQ3hODzRRUMZnwE+YOe9a6/wCr/CiigBI/u1IKKKAEkAxUSdaKKALsYG2nYGelFFUhEiUPRRTArTfdNZE/36KKALFp0q83SiigCjMTv60R8miigDRgAx0qwaKKAEH3DVG670UUAZjfeqSOiigAf71SJRRQBchFXEoooAkNRHrRRQA9Kl7UUUANaoW60UUAKKdRRQAq089KKKAK0vWkj60UUASt0oQ80UUAWo+lPNFFAFeeqjE5oooAs2/arw6UUUAKOlRPRRQAwVIKKKAGtULUUUAC1LRRQA4fdqCTrRRQA1elDdKKKAM+6HzVmz9DRRQBhXv3qXTwN4oooA6m3GEFQ3hODzRRUMZnwE+YOe9a6/6v8KKKAEj+7UgoooASQDFRJ1oooAuxgbadgZ6UUVSESJQ9FFMCtN901kT/AH6KKALFp0q83SiigCjMTv60R8miigDRgAx0qwaKKAEH3DVG670UUAZjfeqSOiigAf71SJRRQBchFXEoooAkNRHrRRQA9Kl7UUUANaoW60UUAKKdRRQAq089KKKAK0vWkj60UUASt0oQ80UUAWo+lPNFFAFeeqjE5oooAs2/arw6UUUAKOlRPRRQAwVIKKKAGtULUUUAC1LRRQA4fdqCTrRRQA1elDdKKKAM+6HzVmz9DRRQBhXv3qXTwN4oooA6m3GEFQ3hODzRRUMZnwE+YOe9a6/6v8KKKAEj+7UgoooASQDFRJ1oooAuxgbadgZ6UUVSESJQ9FFMCtN901kT/foooAsWnSrzdKKKAKMxO/rRHyaKKANGADHSrBoooAQfcNUbrvRRQBmN96pI6KKAB/vVIlFFAFyEVcSiigCQ1EetFFAD0qXtRRQA1qhbrRRQAop1FFACrTz0oooArS9aIic9aKKAL0fSrEIBkAIB+tFFAF4AAYAxRRRUjP/Z
--000000000000b84ac3059fa3c6aa--
I've read the documentation and tons of SO posts. I have no idea why this is taking place.
