Kindle's ‘send to Kindle’ feature getting major security update, users fear third-party integration problems

Amazon’s popular “Send to Kindle” feature, which lets users email documents straight to their Kindle devices, is about to get a big security upgrade. The change is coming on April 1, 2025, and it’s already stirring up some worries among users about how it might mess with third-party services they love.

Right now, users can add partial email addresses or just domains — like “@example.com” — to their approved sender list. That setup has worked great for services like Readwise, which sends content directly to Kindles. But soon, Amazon will only allow full email addresses, such as “[email protected],” to send files. The company says this is all about beefing up security. In an email to customers, Amazon noted, “This change helps ensure that only senders from emails you specifically approve can deliver documents to your Kindle.”

The goal makes sense — keeping your Kindle safe from unwanted files is a plus. But here’s where the trouble starts. Users are nervous that this shift could break integrations with third-party apps. Take Readwise, for example. One user, u/Meraki6, posted on Reddit, “I just got an email from Amazon this morning with an upcoming change that will break Readwise’s send-to-kindle function as it now stands.”

Another user, u/Iromenis, added, “Amazon are tightening up restrictions slowly, so their customer doesn’t understand what is really going on…..” If services like these can’t adapt by using specific email addresses instead of domains, users might find their workflows disrupted.

On top of that, there’s confusion swirling around EPUB files. Some folks say the “Send to Kindle” feature isn’t handling them right anymore. User u/saragrissom complained, “They also no longer accept sending epub files through the send to my kindle app option as they no longer convert them to a readable doc format.” Others, like u/aw9182, disagree, saying EPUBs still work fine through the “Send to Kindle” website. Amazon’s official page lists EPUB as supported, but these mixed reports have users scratching their heads. Is support fading, or is it just a glitch?

With the deadline creeping closer, users and third-party services will need to adjust. Amazon is telling everyone to update their approved email lists with full addresses to keep things running smoothly. For now, it’s a waiting game to see how this all shakes out. Sadly it seems like some convenience might get lost along the way. Feel free to share your thoughts on the change in the comments section below.