[Dovecot] Mbox corruption - Inbox beginning with 'FFrom' or 'FrFrom'

[Erik Kratzenberg]

 > >     -Dovecot.log : Mar 29 11:00:06 Error: POP3(user_login):
 > >        Couldn't init INBOX: Mailbox isn't a valid mbox
 > >     -The mailbox start with either 'FFrom or 'FrFrom'
 >
 > I haven't seen these since v0.99. Are you using also Dovecot
 > deliver? Is anything else than Dovecot modifying the mbox
 > files? I don't really have any great ideas, other than some
 > locking problem if something besides Dovecot does changes..

We're having the same issues on our servers here and it
oddly started at exactly the same time (March 20th or so)
with no changes made by us.

We've upgraded to the latest Dovecot 1.2.11 and are using
Dovecot 'deliver' exclusively.  Tried setting
fsync_disable=no, but the problem persists.  It seems to
only occur for mailboxes that are being accessed via POP3
and leaving mail on the server.

Any further insights?  I'm surprised more people aren't
experiencing this problem.  I don't think we're doing anything 
particularly special.

Thanks,
Erik

----

# 1.2.11: /etc/postfix/dovecot.conf
# OS: FreeBSD 7.2-STABLE i386
base_dir: /var/run/dovecot
protocols: imap imaps pop3 pop3s
ssl_cert_file: sslcert.pem
ssl_key_file: sslcert.pem
ssl_cipher_list: 
ALL:!aNULL:!ADH:!eNULL:!LOW:!EXP:RC4+RSA:+HIGH:+MEDIUM:!SSLv2
disable_plaintext_auth: no
login_dir: /var/run/dovecot/login
login_executable(default): /usr/local/libexec/dovecot/imap-login
login_executable(imap): /usr/local/libexec/dovecot/imap-login
login_executable(pop3): /usr/local/libexec/dovecot/pop3-login
mbox_read_locks: flock
mbox_write_locks: flock
mail_executable(default): /usr/local/libexec/dovecot/imap
mail_executable(imap): /usr/local/libexec/dovecot/imap
mail_executable(pop3): /usr/local/libexec/dovecot/pop3
mail_plugins(default): quota imap_quota
mail_plugins(imap): quota imap_quota
mail_plugins(pop3): quota
mail_plugin_dir(default): /usr/local/lib/dovecot/imap
mail_plugin_dir(imap): /usr/local/lib/dovecot/imap
mail_plugin_dir(pop3): /usr/local/lib/dovecot/pop3
imap_client_workarounds(default): outlook-idle tb-extra-mailbox-sep
imap_client_workarounds(imap): outlook-idle tb-extra-mailbox-sep
imap_client_workarounds(pop3):
pop3_no_flag_updates: yes
pop3_client_workarounds(default):
pop3_client_workarounds(imap):
pop3_client_workarounds(pop3): outlook-no-nuls oe-ns-eoh
lda:
   auth_socket_path: /var/run/dovecot/auth-master
   postmaster_address: postmaster
   mail_plugins: quota
   sendmail_path: /usr/sbin/sendmail
auth default:
   mechanisms: plain login
   master_user_separator: *
   passdb:
     driver: passwd-file
     args: virtual.passwd
   passdb:
     driver: passwd-file
     args: username_format=%n@%l virtual.ip.passwd
   passdb:
     driver: passwd-file
     args: master.passwd
   passdb:
     driver: passwd-file
     args: master.user
     pass: yes
     master: yes
   userdb:
     driver: passwd-file
     args: virtual.passwd
   userdb:
     driver: passwd-file
     args: master.passwd
   socket:
     type: listen
     master:
       path: /var/run/dovecot/auth-master
       mode: 432
       user: vmail
       group: users