Downloading email messages

Can someone please advise how can I download all of my emails from my server directly via ftp . I am the admin of the server and have root access . Can emails be downloaded and decrypted without having password access to individual mailboxes ? I have gone to the following directory but unable where to go from there

Mails are usually stored under /home/user-data/mail/mailboxes. Then look for a folder named after the domain you’re looking for. Finally, there’s a folder per user.

Thanks for the reply but the issue I have is when i go into the mailbox in question and there is a folder called “cur” which i assume is current emails in the mailbox and when doing an ls on that folder i get back a huge list of what im assuming are emails in a weird file type. How do i download/extract that to a readable plain text ?