Maybe I misread the link I shared. Can you clarify:
> PDFs can be converted to the Kindle format so you can take advantage of functionality such as variable font size, annotations, and Whispersync. To have a document converted to Kindle format (.azw), the subject line should be "convert" when e-mailing a personal document to your Send-to-Kindle address.
> PDFs can be converted to the Kindle format so you can take advantage of functionality such as variable font size, annotations, and Whispersync. To have a document converted to Kindle format (.azw), the subject line should be "convert" when e-mailing a personal document to your Send-to-Kindle address.