[Evolution] Evo mail: explanation of old and new file system

["carpetnailz researchintegration org" <carpetnailz researchintegration org>]

I'm still not clear about the relation between the old file system and
storage location and the new. And there doesn't seem to be any
explanation of it in the user documentation for Evolution mail.

For example, tho I thought I had successfully imported all the old mail,
I now have folders that should have lots of mail in them but don't have
any mail.

Where can I find an explanation in lay terms of what the changes were
and how one deals with them? It seems that suddenly Evolution started
doing things differently and users were left to figure things out on
their own.

I understand that the mail is now stored in a different location, but
there seem to be more changes than that--e.g., not using "mbox" any
more. So it's not just that the location has changed--the whole layout
of the mail storage area is different. 

So assuming I can find those old emails in ~/.evolution on one of my old
backups, what's the procedure for moving them to the new format? Do I
just copy everything from the old to the new?  E.g.
    .evolution/mail/local/xLynnOld
    .evolution/mail/local/xLynnOld.cmeta
    .evolution/mail/local/xLynnOld.ibex.index
    .evolution/mail/local/xLynnOld.ev-summary
    .evolution/mail/local/xLynnOld.ev-summary-meta
    .evolution/mail/local/xLynnOld.ibex.index.data
to
    .local/share/evolution/mail/local/.xLynnOld
?

Maybe this is explained somewhere and I just haven't found it? Again, it
would be good if this were in the user documentation--or at least a
reference there to the problem and a good explanation.

Thanks.