Hi all, thanks everyone for the response. I have both a K3 and DX. The K3 will receive emails to my @free.kindle.com address over wifi, converted, free of charge.
The Kindle DX does not have wifi and as montalex confirms, when I send to the @kindle.com address, I only get an email saying the service in unavailable in Canada. Sure, I could email it to @free.kindle to have it converted, but what's the point when we all have Calibre (donate, if you haven't already

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It's a shame as I can browse the web (for free) with impunity on the DX anywhere. Problem would be solved if they just put wifi on the DX.