How can I merging thousands of folders?

[Jerome M Berkman]

We had file system problems, and gave users temporary inboxes while we
fixed the problems.  We have recovered their old inboxes and folders
from tape.  How can we merge them?  This is for 10000+ users.  We are
using ExecMail which is based on an old version of Cyrus, and hope to
migrate to Cyrus soon.

One way I'm thinking of is to make the old inbox/tree the active one,
use UNIX commands to copy the temporary inbox into a subfolder, then
use IMAP "copy" command to copy all the messages from the temporary
inbox, now a subfolder,  to the inbox, and then delete the subfolder.
Can I use the IMAP "copy" command to copy from a subfolder to the
inbox?  We want to the merge to preserve arrival order, flags, etc.

I'd use a similar method for the other folders.  I'll probably use an
expect script for the "copy" commands.  I know I'll have to fiddle with
ACLs, quotas, etc.

Another way might be to dump the info and use IMAP "append", but that
looks much more difficult.

If anyone has done this, or knows of a script to do this, I'd appreciate
a pointer to it.

Thanks.

	- Jerry Berkman, jerry at uclink.berkeley.edu, UC Berkeley