dovecot - Jan 2012 - Proxy login failures

Hi,

I'm using two dovecot pop3/imap proxies in front of our dovecot servers.
Since some days I see many of the following errors in the logs of the two
proxy-servers:

...
dovecot: pop3-login: Error: proxy: Remote "IPV6-IP":110 disconnected:
Connection closed: Connection reset by peer (state=0): user=<myuser>,
method=PLAIN, rip=remote-ip, lip=localip
...
dovecot: imap-login: Error: proxy: Remote "IPV6-IP":143 disconnected:
Connection closed: Connection reset by peer (state=0): user=<myuser>,
method=PLAIN, rip=remote-ip, lip=localip

...


When this happens the Client gets the following error from the proxy:
-ERR [IN-USE] Account is temporarily unavailable.


System-details:
OS: Debian Linux
Proxy: 2.0.5-0~auto+23
Backend: 2.0.13-0~auto+54

Have you any idea what could cause this type of error?

Thanks and regards
Urban Loesch


doveconf -n from one of our backendservers:

# 2.0.13 (02d97fb66047): /etc/dovecot/dovecot.conf
# OS: Linux 2.6.38.8-vs2.3.0.37-rc17-rol-em64t-timerp x86_64 Debian 6.0.2 ext4
auth_cache_negative_ttl = 0
auth_cache_size = 40 M
auth_cache_ttl = 12 hours
auth_mechanisms = plain login
auth_username_format = %Lu
auth_verbose = yes
deliver_log_format = msgid=%m: %$ %p %w
disable_plaintext_auth = no
login_trusted_networks = our Proxy IP's (v4 and v6)
mail_gid = mailstore
mail_location = mdbox:/home/vmail/%d/%n:INDEX=/home/dovecotindex/%d/%n
mail_plugins = " quota mail_log notify zlib"
mail_uid = mailstore
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 ihave imapflags
notify
mdbox_rotate_size = 5 M
passdb {
   args = /etc/dovecot/dovecot-sql-account.conf
   driver = sql
}
plugin {
   mail_log_events = delete undelete expunge copy mailbox_delete mailbox_rename
   mail_log_fields = uid box msgid size from
   mail_log_group_events = no
   quota = dict:Storage used::file:%h/dovecot-quota
   sieve = ~/.dovecot.sieve
   sieve_dir = ~/sieve
   sieve_extensions = +notify +imapflags
   sieve_max_redirects = 10
   zlib_save = gz
   zlib_save_level = 5
}
protocols = imap pop3 lmtp sieve
service imap-login {
   inet_listener imap {
     port = 143
   }
   service_count = 0
   vsz_limit = 256 M
}
service lmtp {
   inet_listener lmtp {
     address = *
     port = 24
   }
   unix_listener /var/spool/postfix/private/dovecot-lmtp {
     group = postfix
     mode = 0666
     user = postfix
   }
   vsz_limit = 512 M
}
service pop3-login {
   inet_listener pop3 {
     port = 110
   }
   service_count = 0
   vsz_limit = 256 M
}
ssl = no
ssl_cert = </etc/ssl/certs/dovecot.pem
ssl_key = </etc/ssl/private/dovecot.pem
userdb {
   args = /etc/dovecot/dovecot-sql-account.conf
   driver = sql
}
protocol lmtp {
   mail_plugins = " quota mail_log notify zlib sieve zlib"
}
protocol imap {
   imap_client_workarounds = tb-extra-mailbox-sep
   mail_max_userip_connections = 40
   mail_plugins = " quota mail_log notify zlib imap_quota imap_zlib"
}
protocol pop3 {
   mail_plugins = " quota mail_log notify zlib"
   pop3_logout_format = bytes_sent=%o top=%t/%p, retr=%r/%b, del=%d/%m, size=%s
uidl_hash=%u
}

On 9.1.2012, at 12.18, Urban Loesch wrote:
> I'm using two dovecot pop3/imap proxies in front of our dovecot
servers.
> Since some days I see many of the following errors in the logs of the two
proxy-servers:
> 
> dovecot: pop3-login: Error: proxy: Remote "IPV6-IP":110
disconnected: Connection closed: Connection reset by peer (state=0):
user=<myuser>, method=PLAIN, rip=remote-ip, lip=localip
> 
> When this happens the Client gets the following error from the proxy:
> -ERR [IN-USE] Account is temporarily unavailable.
The connection to remote server dies before authentication finishes. The reason
for why that happens should be logged by the backend server. Sounds like it
crashes. Check for ANY error messages in backend servers.