[Dovecot] When imapc can't connect to remote IMAP prevents user login (and blocks LDA)

[Marcin Mirosław]

Hi!
I'm using dovecot 2.1.12-r1.
When remote imap server rejects connections then I can't login into
account and MTA can't deliver emails to maildir also.

I'm attaching snippets of logs:
2012-12-15T18:05:43.072594+01:00 meteor dovecot: imap-login: Login:
user=<marcin at mejor.pl>, method=PLAIN,
rip=2001:470:1f0b:1ab3:50af:bef4:6918:78ad, lip=2001:470:1f15:1b61::2,
mpid=32533, TLS, session=<T0GGKOfQCQAgAQRwHwsas1CvvvRpGHit>
2012-12-15T18:05:43.442598+01:00 meteor dovecot: imap(marcin at mejor.pl)
<T0GGKOfQCQAgAQRwHwsas1CvvvRpGHit>: Error: imapc(imap.wp.pl:143): Server
disconnected: Connection reset by peer
2012-12-15T18:05:43.442598+01:00 meteor dovecot: imap(marcin at mejor.pl)
<T0GGKOfQCQAgAQRwHwsas1CvvvRpGHit>: Error: imapc(imap.wp.pl:143):
Authentication failed: Disconnected from server
2012-12-15T18:05:43.442598+01:00 meteor dovecot: imap(marcin at mejor.pl)
<T0GGKOfQCQAgAQRwHwsas1CvvvRpGHit>: Error: imapc: Command failed:
Disconnected from server
2012-12-15T18:05:43.442598+01:00 meteor dovecot: imap(marcin at mejor.pl)
<T0GGKOfQCQAgAQRwHwsas1CvvvRpGHit>: Error: user marcin at mejor.pl:
Initialization failed: Namespace 'xxx-wp-pl.': imapc: LIST failed:
Internal error occurred. Refer to server log for more information.
[2012-12-15 18:05:43]
2012-12-15T18:05:43.442598+01:00 meteor dovecot: imap(marcin at mejor.pl)
<T0GGKOfQCQAgAQRwHwsas1CvvvRpGHit>: Error: Invalid user settings. Refer
to server log for more information.

And snippet when LDA tries to deliver email:
2012-12-15T18:00:54.689877+01:00 meteor dovecot: lda(marcin at mejor.pl)
<>: Error: imapc(imap.wp.pl:143): Server disconnected: Connection reset
by peer
2012-12-15T18:00:54.689877+01:00 meteor dovecot: lda(marcin at mejor.pl)
<>: Error: imapc(imap.wp.pl:143): Authentication failed: Disconnected
from server
2012-12-15T18:00:54.689877+01:00 meteor dovecot: lda(marcin at mejor.pl)
<>: Error: imapc: Command failed: Disconnected from server
2012-12-15T18:00:54.689877+01:00 meteor dovecot: lda(marcin at mejor.pl)
<>: Error: user marcin at mejor.pl: Initialization failed: Namespace
'xxx-wp-pl.': imapc:
 LIST failed: Internal error occurred. Refer to server log for more
information. [2012-12-15 18:00:54]
2012-12-15T18:00:54.689877+01:00 meteor dovecot: lda(marcin at mejor.pl)
<>: Fatal: Invalid user settings. Refer to server log for more information.

I'd like to ask is this behavior correct?
Thanks,
Marcin

doveconf -n:

# 2.1.12: /etc/dovecot/dovecot.conf
# OS: Linux 3.6.8-hardened x86_64 Gentoo Base System release 2.1
auth_cache_size = 1 k
auth_mechanisms = login digest-md5 cram-md5 plain
deliver_log_format = msgid=%m: from=%f: phys=%p: virt=%w %$
dict {
  quota = pgsql:/etc/dovecot/dovecot-dict-sql.conf.ext
}
first_valid_uid = 8
last_valid_uid = 8
lda_mailbox_autocreate = yes
lda_mailbox_autosubscribe = yes
mail_attachment_dir = /dane/domeny/zalaczniki
mail_attachment_min_size = 10000 k
mail_cache_min_mail_count = 20
mail_gid = mail
mail_log_prefix = "%s(%u) <%{session}>: "
mail_plugins = autocreate quota notify mail_log stats zlib
mail_privileged_group = mail
mail_uid = mail
maildir_stat_dirs = yes
managesieve_notify_capability = mailto
managesieve_sieve_capability = fileinto reject envelope
encoded-character vacation subaddress comparator-i;ascii-numeric
relational regex imap4flags copy incl
ude variables body enotify environment mailbox date ihave
mdbox_preallocate_space = yes
mdbox_rotate_interval = 60 days
mdbox_rotate_size = 50 M
namespace inbox {
  inbox = yes
  list = yes
  location =
  mailbox Drafts {
    special_use = \Drafts
  }
  mailbox Junk {
    special_use = \Junk
  }
  mailbox Sent {
    special_use = \Sent
  }
  mailbox "Sent Messages" {
    special_use = \Sent
  }
  mailbox Trash {
    special_use = \Trash
  }
  prefix =
  separator = .
  subscriptions = yes
}
passdb {
  args = /etc/dovecot/dovecot-sql.conf.ext
  driver = sql
}
plugin {
  autocreate = Trash
  autocreate2 = Spam
  autocreate3 = Sent
  autocreate4 = Drafts
  autosubscribe = Trash
  autosubscribe2 = Spam
  autosubscribe3 = Sent
  autosubscribe4 = Drafts
  quota = dict:User quota::proxy::quota
  quota_exceeded_message = Quota exceeded / Skrzynka odbiorcy jest
przepelniona, wiadomosc nie zostala dostarczona
  sieve = ~/.dovecot.sieve
  sieve_dir = ~/sieve
  stats_command_min_time = 1 mins
  stats_domain_min_time = 12 hours
  stats_ip_min_time = 12 hours
  stats_memory_limit = 1M
  stats_refresh = 30 s
  stats_session_min_time = 15 mins
  stats_track_cmds = yes
  stats_user_min_time = 1 hours
  zlib_save = gz
}
postmaster_address = postmaster at mejor.pl
protocols = imap pop3 sieve
service auth {
  unix_listener auth-userdb {
    group = mail
    mode = 0660
    user = root
  }
}
service dict {
  unix_listener dict {
    user = mail
  }
}
service stats {
  fifo_listener stats-mail {
    mode = 0600
    user = mail
  }
}
ssl_cert = </etc/ssl/gwiazdka.mejor.pl.pem
ssl_key = </etc/ssl/gwiazdka.mejor.pl.pem
userdb {
  driver = prefetch
}
userdb {
  args = /etc/dovecot/dovecot-sql.conf.ext
  driver = sql
}
verbose_proctitle = yes
protocol lda {
  mail_plugins = autocreate quota notify mail_log stats zlib sieve
}
protocol imap {
  mail_max_userip_connections = 25
  mail_plugins = autocreate quota notify mail_log stats zlib imap_quota
imap_stats imap_zlib
}