In my Mac Mail I have all my emails saved to my Mac, as opposed to on my mail server using iMap.

All the emails are organised with a large number of folders and sub folders, again all of which are saved straight to my Mac.

I wish to save all of the individual emails in a folder on an external hard drive as I am moving to a new Mac and want to have access to these emails, but not import them to Mac Mail on my new Mac.

If you select an individual email in Mac Mail, then drag and drop it to a desktop folder, for example, it saves it as an email which you can open from the desktop folder without it having to be stored in your Mac Mail. If you select multiple emails and drag and drop, only one email is transferred.

How can I do this drag and drop method for all the folders and all emails within those folders, to save them on an external hard drive.

I don't want to export all the emails from my current Mac, then reimport them to my new Mac Mail. I want to be able to access all the emails in their structure, but through my hard drive instead of having them show in Mac Mail.

Guidance appreciated