title_body: Converting a gmail email to kindle as readable document
upvoted_answer: The best solution is to use a PDF via Send to Kindle Email Address using the steps below in order to retain the functions you are asking for- variable size font, annotations, etc.
  
  
  Open the Gmail email you want to transfer and click the print button
  at the top right corner. 
  From the print screen, change the printer option to PDF and save. 
  You must have a Kindle
  Send the PDF as an attachment to your Kindle Paperwhite via your Send to Kindle Email Address BUT you must put convert in the subject line. This automatically converts the PDF to Kindle format retaining the features mentioned above.
  
  
  Just as a heads up, Amazon may limit how many documents you send and store through the Kindle Personal Document Service, so I would routinely delete old documents and make sure you have backups on your computer of any personal document you might want at a later date, just in case Amazon deletes them for any reason. 
  
  There is also a Kindle Convert app you can download from https://www.amazon.com/gp/product/B00K7HEGZ6