Last updated: 16 December 2012

Amazon appears to have fixed the issue affecting their servers, we’re seeing no more bounces now.

Amazon is experiencing delivery issues which is affecting our Push to Kindle service. Many emails are bouncing with the following message:

The following message to <xxx@free.kindle.com> was undeliverable.
The reason for the problem:
5.1.0 - Unknown address error 550-'5.1.1 <xxx@free.kindle.com>... User unknown'

Reporting-MTA: dns; smtp-border-fw-31001.sea31.amazon.com

Final-Recipient: rfc822;xxx@free.kindle.com
Action: failed
Status: 5.0.0 (permanent failure)
...
Diagnostic-Code: smtp; 5.1.0 - Unknown address error 550-'5.1.1 <xxx@free.kindle.com>... User unknown' (delivery attempts: 0)

The error says ‘user unknown’ but the user clearly exists in Amazon’s system. This problem appears to have started around November 16. Here’s a chart from our email service provider showing a sudden increase in bounces from Amazon’s servers:

The current workaround is to send to your @kindle.com address — read update #2 to make sure you do not get charged by Amazon.

We’ll update again here when we know more. Sorry for the inconvenience.

If you’d like to help get this fixed sooner, please contact Amazon’s Kindle support (UK, US) and tell them you’re experiencing emails bouncing when sent to your @free.kindle.com email.