[Dovecot] New mail not appearing consistently in Outlook 2003

[Karl von Randow]

Hi all,

I have continuously experienced a new mail not appearing problem in Outlook
2003 on Windows XP. Using Dovecot 0.99.14 on Debian Sarge and now in 1.0rc26
and rc27.

The problem exhibits itself as:
Some new mail is randomly(?) not shown in my mailbox. More new mail does
appear, so it's difficult to know when a message has been missed. If I
restart Outlook the missed new messages will appear as unread in the order
where they should have been received in my inbox.

I use secure imap. I get email through my inbox (receipts from a website
we're testing, at its peak maybe 2-3 a minute) that are moved into another
mailbox using a rule in Outlook. These are often the messages that are
missed as above, but it often includes other email as well.

The mail box format is mbox on the server. The mail delivery is by exim4
from Debian Sarge. I wondered if there was a locking problem between exim4
and dovecot? My transport in exim4 for delivering the mail is:
mail_spool_home:
  debug_print = "T: appendfile for $local_part@$domain"
  driver = appendfile
  file = /home/vmail/$domain/$local_part/INBOX
  delivery_date_add
  envelope_to_add
  return_path_add
  group = mail
  mode = 0660
  mode_fail_narrower = false

The problem is reproducable in that I see the problem occur everyday. I am
about to compile and install rc28 to see if that improves matters. I'd
appreciate any help resolving the problem!

Here is my dovecot.conf:

# /usr/local/etc/dovecot.conf
protocols: pop3 imap imaps
disable_plaintext_auth: no
login_dir: /usr/local/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
mail_extra_groups: mail
mail_location: mbox:/home/vmail/%d/%n/mail/:INBOX=/home/vmail/%d/%n/INBOX
mbox_dirty_syncs: no
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_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 delay-newmail
imap_client_workarounds(imap): outlook-idle delay-newmail
imap_client_workarounds(pop3): outlook-idle
pop3_uidl_format(default):
pop3_uidl_format(imap):
pop3_uidl_format(pop3): %08Xu%08Xv
auth default:
  passdb:
    driver: passwd-file
    args: /etc/vmail.passwd
  userdb:
    driver: static
    args: uid=1064 gid=1001 home=/home/vmail/%d/%u