Originally Posted by RichieTheK
Thank you all for your comments.
I figured out what I was doing wrong (operator error...). I was not selecting the format to send, I just clicked "OK", which assumed I wanted to send an epub format (the first in the list), necessitating a conversion of those books that did not have epub formats available. I was misinterpreting the message "No suitable formats" to mean that the formats I selected were not compatible with the device. The message actually means that the formats available for the books that I wanted to send did not include the format selected in the popup.
This, however, presents another problem. The popup only allows the selection of one format. If I have selected several books of different formats to send, I can only choose one format in the popup. Books not of this format will either be converted or not sent, depending on how I respond to the autoconversion notification popup.
I really think that declining the autoconversion should send the books unconverted.
That message says NO ticked formats were available.
The order of the DEVICE plugin list sets the preference ORDER
it says, if all or any of the ticked formats exist, send the First with a tick.
If you prefer (and HAVE) Mobi over EPUB then that should be first or it will send EPUB. Don't have either, then it will convert to the first.