[Dovecot] IMAP message ID bad for very old message

[a.smith at ukgrid.net]

Quoting Timo Sirainen <tss at iki.fi>:
> Have you checked if there are any errors in Dovecot logs? There are some
> reasons why Dovecot might give a new UID to an existing mail. dovecot -n
> output might also be useful.
>
>

Hi Timo,

   thanks for the reply. I just checked and the file names are correct  
for the mails to be ordered chronologically, so nothing weird going on  
there that would cause a prob.
I can't see any errors relating to this in the logs, but my logs a  
several thousand lines per day so is there any particular error  
message I should be looking for? A grep -i err doesn't show anything  
interesting...

Here is a the output of dovecot -n:

# dovecot -n
# 2.0.11: /usr/local/etc/dovecot/dovecot.conf
# OS: FreeBSD 8.2-RELEASE amd64  zfs
auth_username_format = %Lu
disable_plaintext_auth = no
dotlock_use_excl = no
first_valid_gid = 1000
first_valid_uid = 1000
lock_method = dotlock
mail_fsync = always
mail_location = maildir:/var/spool/mail/%d/%u
mail_nfs_index = yes
mail_nfs_storage = yes
mail_privileged_group = vmail
managesieve_notify_capability = mailto
managesieve_sieve_capability = fileinto reject envelope  
encoded-character vacation subaddress comparator-i;ascii-numeric  
relational regex imap4flags copy include variables body enotify  
environment mailbox date
mmap_disable = yes
passdb {
   args = /usr/local/etc/dovecot/dovecot-sql.conf
   driver = sql
}
plugin/fts = squat
plugin/fts_squat = partial=4 full=10
protocols = imap pop3
service auth {
   unix_listener auth-client {
     mode = 0660
   }
   unix_listener auth-master {
     mode = 0600
   }
   user = root
}
service imap {
   vsz_limit = 1 G
}
service pop3 {
   vsz_limit = 1 G
}
ssl_ca = </usr/local/etc/ssl.crt/ca-bundle.crt
ssl_cert = </usr/local/etc/ssl.crt/pop3.crt
ssl_key = </usr/local/etc/ssl.key/pop3.key
userdb {
   args = /usr/local/etc/dovecot/dovecot-sql.conf
   driver = sql
}
protocol imap {
   imap_client_workarounds = delay-newmail tb-extra-mailbox-sep
   mail_plugins = fts fts_squat
   ssl = yes
   ssl_cert = </usr/local/etc/ssl.crt/imap.crt
   ssl_key = </usr/local/etc/ssl.key/imap.key
}
protocol pop3 {
   pop3_client_workarounds = outlook-no-nuls oe-ns-eoh
   pop3_uidl_format = %08Xu%08Xv
   ssl = yes
   ssl_cert = </usr/local/etc/ssl.crt/pop3.crt
   ssl_key = </usr/local/etc/ssl.key/pop3.key
}
protocol lda {
   sendmail_path = /usr/local/sbin/exim
}


thanks Andy.