NodeMailer plus Apple Mail -- how to create a Draft email

Trying to use NodeMailer to create a Draft email in Apple Mail.

The following approaches have not yet been successful:

• Using NodeMailer's mail option saveToDrafts: true
• Saving an email as a .eml file in the Finder, using AppleScript to open the file and convert it to a Draft (Note: Creating and opening in Apple Mail works just fine, but the result is a read-only, unsendable email that must be converted manually to a Draft using Apple Mails "Move to..." button. Trying to get rid of that manual step.

NodeJS package imapflow's append can be used to push an .eml file (created, say, by nodemailer's mailcomposer).