My goal is:
Even if I do not use Macs in the future, I should be able to see all my messages as plain text files. This is the most important key. I want plain text files of all my messages, not some proprietary Mac format.
I have already created a Backup Mailbox on my mac and copied all my mail over to this new "backup" mailbox....but how can I actually copy all my email messages into Dropbox?
When you got your mail app open, you can select all your messages and drag them into a folder. You can then compress the folder and upload that to dropbox.
The downside of the compression is that you will need to download the file before you can see it's contents. If you drag the folder into your dropbox folder, you should be able to view them online.
Better yet if you import the files into evernote (www.evernote.com) you will be able to search through them. Evernote is also cloud based so no matter what machine you use you will always have access to those messages.
Otherwise you can also create a Gmail account and upload them into that account via IMAP which again offers you a great search tool.
Many options available to you there. Good Luck!
Apple Mail does not use a proprietary format. All the mails are stored as is (text). Just browse to
to see the messages. Attachments are also stored as normal files.
You can just copy them
That's the problem - here we are in 2017 and I still can't simply export the mail to a folder on another cloud service like DropBox and access the emails - they become this bullshit text crap impossible to read.
I'm sick of being extorted by Apple to buy more icloud space and I lose files every time I upgrade my OS with Apple and do not trust their system to keep my email back as far as I need (years).
By 2017 they should give a shit about their users and allow them freedom to be untethered to the nut sack that is iCloud.