Sending books to your Kindle is supposed to be simple: email the file to your @kindle.com address, and it appears on your device. Except when it does not, because the file is too large and your email provider silently rejects it.
This is one of the most common frustrations for Kindle owners with large EPUB libraries. The good news is there is a clean, one-step fix.
Why Do EPUBs Bounce When You Email Them to Kindle?
The problem is not Amazon; it is your email provider. Gmail, Outlook, Apple Mail, and most other providers cap email attachments at 25 MB. If your EPUB exceeds that, the email is rejected before it ever reaches Amazon's servers.
And many EPUBs do exceed 25 MB, often by a lot:
- Graphic novels and manga: 80–200 MB
- Illustrated travel guides: 40–100 MB
- Cookbooks with photography: 30–80 MB
- Children's picture books: 20–60 MB
Even the official Send to Kindle app and website, which have a higher 200 MB limit, can still fail for exceptionally large files or slow connections.
All the Ways to Send an EPUB to Kindle: Size Limits Compared
| Method | Size Limit | Notes |
|---|---|---|
| Email to @kindle.com | ~25 MB | Limited by your email provider, not Amazon |
| Send to Kindle app (iOS/Android) | 200 MB | Most reliable for large files |
| Send to Kindle website | 200 MB | sendtoreader.amazon.com |
| USB cable transfer | No limit | Requires a computer |
| Calibre + USB | No limit | Powerful but desktop-only |
If you prefer emailing (the most convenient method), the real solution is to get your EPUB under the 25 MB limit before you send it.
The Fastest Fix: Compress the EPUB First with LiteBook
LiteBook is a free iOS app that compresses EPUB files by up to 70% directly on your iPhone or iPad: no desktop, no cloud, no waiting. After compression, an 85 MB graphic novel becomes around 26 MB. A 60 MB travel guide drops to around 24 MB. Both comfortably under the email limit.
Step-by-Step: Compress and Send to Kindle in Under 2 Minutes
- 1Download LiteBook
Get LiteBook free from the App Store on your iPhone or iPad.
- 2Import your EPUB
Tap Import Books and select the file from your Files app or iCloud Drive. You can also share an EPUB directly to LiteBook from any other app using the iOS Share Sheet.
- 3Select Smart Compression
For most books, Smart Compression delivers the best results: maximum size reduction optimised for e-reader screens. Use Lossless mode if you want zero quality change.
- 4Tap Compress
LiteBook processes the file locally in seconds. You will see the exact new file size and how much space was saved.
- 5Share to Kindle
Tap the share icon on your compressed file and choose Mail or the Send to Kindle app. The smaller file will go through without bouncing.
Pro Tip: Use the Send to Kindle App for Files Over 25 MB
If you regularly work with very large files, install the free Send to Kindle app (available on iOS). It accepts files up to 200 MB and syncs directly to your device without going through email. After compressing with LiteBook, tap Share, then Send to Kindle.
This combination; compress in LiteBook, then send via the Send to Kindle app; is the smoothest, most reliable workflow for getting large illustrated books onto your Kindle from an iPhone.
Frequently Asked Questions
- What is the Kindle email attachment size limit?
- Amazon's Send to Kindle service accepts up to 200 MB via the app or website. Email via your @kindle.com address is limited to roughly 25 MB by your email provider. Compressing your EPUB first is the easiest way to stay under either limit.
- Why does my EPUB bounce when I email it to Kindle?
- Email providers like Gmail and Outlook cap attachments at 25 MB. Large EPUBs, such as graphic novels, cookbooks, and travel guides, commonly exceed this. The solution is to compress the EPUB before sending.
- Does Amazon re-compress my EPUB when I send it?
- Amazon may convert your EPUB to AZW3 format, but they do not systematically optimise image sizes. You will get better, more predictable results by compressing yourself with LiteBook first.
- Can I send a compressed EPUB directly from LiteBook to Kindle?
- Yes. After compressing, tap the share icon and select the Send to Kindle app or share via email to your Kindle address, all from within LiteBook.
Conclusion
Bounced emails are not a Kindle problem; they are an EPUB size problem. And size problems have a simple solution: compress your file before you send it.
With LiteBook on your iPhone, the whole process takes under two minutes and works completely offline. Compress, share, read.
Stop fighting attachment limits.
Compress your EPUB with LiteBook and send it straight to your Kindle; no bouncing, no cables.
Download LiteBook — Free