Problem: mail moved by thunderbird script is invisible to mail clients, but in cur directory

[David Gessel]

Over the last year I've had a script moving old mail (120 days) into my 
annual archive folder.  This is the first year I've done this with Dovecot, 
previously it was running against Cyrus.

There's nothing particularly clever: a few conditions to match, then "move 
message to" the appropriate archive folder.  There's one for every year 
from 2000 to 2015.  2015 is just barely ahead of need.  2014 has about a 
year's mail in the cur directory.

The 2000-2013 folders were filled by Cyrus and were migrated over using 
IMAP Migrate.  They're fine, and read normally.

The 2014 layout looks normal to me
# ls
cur                     dovecot-uidlist         dovecot.index.cache 
dovecot.index.log.2     new
dovecot-keywords        dovecot.index           dovecot.index.log 
maildirfolder           tmp


Permissions are the same as every other folder, as is owner:
drw-r-----   2 vmail  vmail   9.6K Apr 12 21:13 cur

and
#  ls | wc -l
    9822


I've checked with Thunderbird, Mulberry, Claws, and Sylpheed - none can 
read the directory.

The files look normal: 2014/cur
1426411329.M123928P26360.host.domain.com,S=3523,W=3591:2,R

More or less the same as a working directory: 2013/cur
1405500734.M958596P27867.host.domain.com,S=794,W=819:2,RS

I've run

# doveadm force-resync -u user .archives.2014

and nothing changed.

I'm at a bit of a loss since no client can read them, something like moving 
them to another folder and back is a little complicated.  Any hints?