[Dovecot] disconnect error

[ML]

a user complain about suddent disconnect error from time to time (he's  
using pop3 with Apple Mail)

Looking at dovecot logs I discover that, each time the error shows up  
for him, I have this :

dovecot: pop3[95137]: Info: user=<dan at userdomain.com> Disconnected  
top=0/0, retr=0/0, del=0/4, size=127101

but all other "regular" pop3 session looks like this one :

dovecot: pop3[94777]: Info: user=<dan at userdomain.com> Disconnected:  
Logged out top=0/0, retr=0/0, del=0/3, size=67947


What is the difference beetween "Disconnected: Logged out" and  
"Disconnected" and how can I solve this ?

Thanks for any tips...


# dovecot.conf :
protocols: imap pop3 imaps pop3s
disable_plaintext_auth: no
shutdown_clients: 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
login_greeting_capability(default): yes
login_greeting_capability(imap): yes
login_greeting_capability(pop3): no
login_processes_count: 10
verbose_proctitle: yes
first_valid_uid: 26
last_valid_uid: 26
first_valid_gid: 6
last_valid_gid: 6
mail_privileged_group: mail
mail_location: maildir:/usr/local/mail/%d/%u
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 antispam
mail_plugins(imap): quota imap_quota antispam
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
mail_log_prefix: %Ls[%p]: Info: user=<%u>
imap_client_workarounds(default): delay-newmail outlook-idle netscape- 
eoh tb-extra-mailbox-sep
imap_client_workarounds(imap): delay-newmail outlook-idle netscape-eoh  
tb-extra-mailbox-sep
imap_client_workarounds(pop3): outlook-idle
pop3_uidl_format(default):
pop3_uidl_format(imap):
pop3_uidl_format(pop3): UID%u-%v
pop3_client_workarounds(default):
pop3_client_workarounds(imap):
pop3_client_workarounds(pop3): outlook-no-nuls oe-ns-eoh
namespace:
   type: private
   prefix: INBOX.
   inbox: yes
auth default:
   mechanisms: plain login digest-md5 cram-md5
   user: nobody
   verbose: yes
   debug: yes
   passdb:
     driver: sql
     args: /usr/local/etc/dovecot-sql.conf
   userdb:
     driver: sql
     args: /usr/local/etc/dovecot-sql.conf
   userdb:
     driver: prefetch
   socket:
     type: listen
     client:
       path: /var/run/dovecot/auth-client
       mode: 384
     master:
       path: /var/run/dovecot/auth-master
       mode: 384
       user: mailnull
       group: mail
plugin:
   sieve: /usr/local/mail/.dovecot.sieve
   trash: /usr/local/etc/dovecot-trash.conf
   antispam_signature: X-DSPAM-Signature
   antispam_trash: trash;Trash;Deleted Items
   antispam_spam: Junk;Spam;junk;spam;SPAM;SpamTrain
   antispam_unsure: Draft;draft
   antispam_mail_tmpdir: /tmp
   antispam_mail_spam: spam at localhost
   antispam_mail_notspam: nospam at localhost
   antispam_mail_sendmail: /usr/sbin/sendmail