Originally Posted by HarryT
With modern versions of Android that unfortunately doesn't work, because newer Android devices don't mount as a drive, but as a "portable device", which Calibre can't recognize. You have to use some other method to get your books to the Kindle app, such as copying the files to the "Kindle" folder using Windows Explorer, using the Calibre server, or using Amazon's "Personal Documents" facility.
That's not quite true, as I was able to transfer my books to a folder on my Android device usuing the latest version of calibre which takes MTP imto account. When i connected my device, I had to upload my drivers (had to find them manually on the list in Windows), create an expression that would send tge books to the proper folder, and I'm set to go.
I'd post the steps and screenshots but I'm travelling now and don't have access to my desktop. Perhaps when I get home, if someone doesn't do it before me.
Eta: actually, I just remembered the instructions I followed; they are for a rooted Gtablet but work for other android devices as well.
HOW TO INSTALL MTP DRIVERS
Open Device Manager and find the offending TeamDRH MTP device.
Right-Click and choose Update Driver Software
Then choose Browse My Computer for Driver Software
Then click Let Me Pick From a List of Device Drivers on My Computer
Then choose All Devices
When that list populates choose Standard MTP Device followed by MTP USB Device
Click Yes to the warning and VIOLA!
That should enadble your MTP device to be recognized by the latest calibre; I don't think older versions work. After that, I had to go to the device interface plugin, and edit both the Android device interface and MTP device interface. I can't remember what expression I used in those plugins, sorry.