Locations for folders, etc, for previously-existing users

[Don Levey]

If this has been covered elsewhere, please excuse me - I have not turned
up the info I need in any of my searches.  Recently my CentOS home server
crashed, and in the process of reconstruction I have brought up a new
configuration into which I am trying to migrate the data from my old
users.  What's more, my old server was first configured over a decade ago,
and when it came time to rebuild I decided on Cyrus rather than the
previously-installed Dovecot (as I've found Cyrus is now the default on
CentOS).  Before I worry about the various client applications trying to
connect, am am working on getting Squirrelmail up and running properly.

Now, the details.  At the moment, I am able to send via Squirrelmail, but
am unable to access the existing mail inbox or the numerous folders my
users have previously created on the server (currently reading mail via
mutt, inbox only).  This appears to be due to the differing directory
structures in the two different IMAP packages.  While it might be nice to
simply alter a config var and have everything magically appear, I am
certainly willing to manually move data files to the new appropriate
locations - the problem is that I don't know the locations.

Previously, I had the following directory structure
/home/user
        ~mail (I honestly don't know how it got set up this way; the tilda
gives me the willies)
                Folder 1 (data file with mail messages)
                Folder 2
                Folder 3
                .imap
                        Folder 1 (dir)
                        Folder 2 (dir)
                        Folder 3 (dir)
                                dovecot.index
                                dovecot.index.cache
                                dovecot.index.log

..And so on.  I know that the Cyrus structure seems to use:
        /var/spool/imap/user/<u>/<username>

but that <username> file seems to be... not a data file. Is there a way to
migrate the old configuration into the new one?  I'm not sure what other
info will be necessary from me.

CentOS 7 (3.10.0-123.9.3.el7.x86_64)
cyrus-imapd              2.4.17-7.el7
cyrus-imapd-utils        2.4.17-7.el7
cyrus-sasl               2.1.26-17.el7
cyrus-sasl-gssapi        2.1.26-17.el7
cyrus-sasl-lib           2.1.26-17.el7
cyrus-sasl-md5           2.1.26-17.el7
cyrus-sasl-plain         2.1.26-17.el7
cyrus-sasl-scram         2.1.26-17.el7
squirrelmail             1.4.22

Thanks in advance,
 -Don