You're on Linux. "yum install fetchmail; man fetchmail" should get you
pretty far.

Any IMAP system that can handle multiple accounts should then allow
you to move messages back, and forth, to multiple accounts: this was
built into Thunderbird, as I remember from some years back.

On Fri, Mar 6, 2015 at 6:58 PM, Yasha Karant <[log in to unmask]> wrote:
> My department is being forced by the university administrative IT unit to MS
> Office365 distributed server ("cloud") email service, as I have communicated
> in a previous query.  We are now being advised by others who have been
> forced to do this -- but of course not by IT -- to backup all of our email.
> I use Mozilla Thunderbird, incoming IMAP, outgoing to a designated SMTP
> server.   I have found
>
> http://www.beyondinbox.com/beyondinbox-download.html
>
> licensed for fee that claims to function under Linux, MacOS X, and MS
> Windows for this purpose.  There are concerns to find a viable
> licensed-for-free product that will copy IMAP folders and all of the
> contents thereof to a local harddrive directory/file structure and that can
> restore these same IMAP folders and the contents thereof back to a remote
> IMAP service -- thus guarding against loss -- up to the last backup snapshot
> -- of all email.
>
> Has anyone any experience with the above application?  is there a licensed
> for free reliable, viable alternative, GUI preferred, for Linux?
>
> Yasha Karant