Email to kindle - same email works for some, not others
Each morning I email an ebook via a Gmail address to multiple kindles. I use the appropriate @free.kindle.com & @kindle.com address depending on the kindle type. I can see on my email account that the email (with the ebook) was correctly sent to all the devices, however it is only received by 3 (out of 5) of them.
Has anybody any idea why some receive it & some don't?