Bizarre Send-to-Kindle problems

BradWaite · 11-22-2016, 05:50 PM

Long-time user of Calibre here.

Sometime in the last year Calibre stopped emailing books to my Kindle. I don't know if it was related to a Calibre upgrade, or something else, but I spent some time today to do some troubleshooting.

First, my SMTP server settings are correct. I happen to run the mail server and have verified via logs that the emails are properly going through qmail as expected.

I've verified the send-to-kindle email address set up in Calibre, and have set the format to MOBI only.

Every book sent from Calibre disappears into a black hole. The job log file indicates that the email was sent successfully, and the server logs show that Amazon's server accepted it.

But it never shows up on my Kindle.

When I save the MOBI file to disk and send it via Thunderbird, my Kindle has it in minutes.

I then tried sending the book to myself from Calibre and then forwarding it in Thunderbird to my Kindle address. That also worked.

After comparing the raw email received from Calibre and the same email sent from Thunderbird, here's what I've noticed so far.

The Calibre email only has base64-encoded MIME parts, including the "Attached, you will find the e-book" part. The Thunderbird email has that message as both text/plain and text/HTML with 7bit encoding (based on my Tbird prefs), but not as base64 encoded. Both messages have the MOBI as application/x-mobipocket-ebook base64 encoded.

I'm stumped. Does Amazon require a plaintext portion to accept a book?

kovidgoyal · 11-22-2016, 07:51 PM

A few months ago amazon changed their spam detection algorithms which caused lots of email to amazon setps to stop working. Search these forums and you will find lots of instances of this. The current best way to send email to amazon is to use GMX/GMail/whatever as the mail relay, as this tends to get past their spam filters with higher probability. See the FAQ entry in the calibre manual on email sending for more details.

BradWaite · 11-23-2016, 02:34 AM

Thanks for the reply, Kovid.

Based on the fact that eBooks sent through the same MTA with a different client are getting through, it stands to reason that simply changing how Calibre's emails are formatted would solve this problem, no?

kovidgoyal · 11-23-2016, 04:54 AM

Until they decide to tweak their algorithm again. I refuse to play whack-a-mole with amazon.

11-22-2016, 05:50 PM	#1
BradWaite Member Posts: 10 Karma: 10 Join Date: Jan 2012 Device: Kindle	Bizarre Send-to-Kindle problems Long-time user of Calibre here. Sometime in the last year Calibre stopped emailing books to my Kindle. I don't know if it was related to a Calibre upgrade, or something else, but I spent some time today to do some troubleshooting. First, my SMTP server settings are correct. I happen to run the mail server and have verified via logs that the emails are properly going through qmail as expected. I've verified the send-to-kindle email address set up in Calibre, and have set the format to MOBI only. Every book sent from Calibre disappears into a black hole. The job log file indicates that the email was sent successfully, and the server logs show that Amazon's server accepted it. But it never shows up on my Kindle. When I save the MOBI file to disk and send it via Thunderbird, my Kindle has it in minutes. I then tried sending the book to myself from Calibre and then forwarding it in Thunderbird to my Kindle address. That also worked. After comparing the raw email received from Calibre and the same email sent from Thunderbird, here's what I've noticed so far. The Calibre email only has base64-encoded MIME parts, including the "Attached, you will find the e-book" part. The Thunderbird email has that message as both text/plain and text/HTML with 7bit encoding (based on my Tbird prefs), but not as base64 encoded. Both messages have the MOBI as application/x-mobipocket-ebook base64 encoded. I'm stumped. Does Amazon require a plaintext portion to accept a book?

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11-22-2016, 07:51 PM	#2
kovidgoyal creator of calibre Posts: 43,826 Karma: 22666666 Join Date: Oct 2006 Location: Mumbai, India Device: Various	A few months ago amazon changed their spam detection algorithms which caused lots of email to amazon setps to stop working. Search these forums and you will find lots of instances of this. The current best way to send email to amazon is to use GMX/GMail/whatever as the mail relay, as this tends to get past their spam filters with higher probability. See the FAQ entry in the calibre manual on email sending for more details.

11-23-2016, 02:34 AM	#3
BradWaite Member Posts: 10 Karma: 10 Join Date: Jan 2012 Device: Kindle	Thanks for the reply, Kovid. Based on the fact that eBooks sent through the same MTA with a different client are getting through, it stands to reason that simply changing how Calibre's emails are formatted would solve this problem, no?

11-23-2016, 04:54 AM	#4
kovidgoyal creator of calibre Posts: 43,826 Karma: 22666666 Join Date: Oct 2006 Location: Mumbai, India Device: Various	Until they decide to tweak their algorithm again. I refuse to play whack-a-mole with amazon.

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