[Dovecot] How to solve a "Connection queue full problem" - dovecot version 2.0.16

[Didier Gervaise]

Hello,

I put in production dovecot yesterday.
After an hour, nobody could log in ("Max number of imap connection" 
error message on Thunderbird)

Afterward, I found these messages in the logs:
  Jan 10 09:21:20 mailsrv dovecot: [ID 583609 mail.info] imap-login: 
Disconnected: Connection queue full (no auth attempts): 
rip=xxx.xxx.xxx.xxx, lip=xxx.xxx.xxx.xxx

In the panic, I changed these values in 
/usr/local/etc/dovecot/conf.d/10-master.conf
  default_process_limit = 20000
  default_client_limit = 20000

This apparently solved the problem but now I have these messages when I 
start dovecot:

  Jan 11 14:41:08 mailsrvspare dovecot: [ID 583609 mail.info] master: 
Dovecot v2.0.15 starting up
  Jan 11 14:41:08 mailsrvspare dovecot: [ID 583609 mail.warning] config: 
Warning: service auth { client_limit=4096 } is lower than required under 
max. load (103024)
  Jan 11 14:41:08 mailsrvspare dovecot: [ID 583609 mail.warning] config: 
Warning: service anvil { client_limit=20000 } is lower than required 
under max. load (60003)

What should I do ?
  - adding "service_count = 0" in service imap-login { ...  }   and 
removing the modifications I did in 10-master.conf ?
  or
- should I configure differently default_process_limit and 
default_client_limit ?

It is a small site (about 1000 users). Currently I have 666 imap 
processes and 136 imap-login processes.

Additionnal infos:

The Server is a Solaris 10 Sun X4540 32GB RAM

mailsrv:~ % /usr/local/sbin/dovecot -n
# 2.0.16: /usr/local/etc/dovecot/dovecot.conf
doveconf: Warning: service auth { client_limit=4096 } is lower than 
required under max. load (103024)
doveconf: Warning: service anvil { client_limit=20000 } is lower than 
required under max. load (60003)
# OS: SunOS 5.10 i86pc
default_client_limit = 20000
default_process_limit = 20000
disable_plaintext_auth = no
first_valid_uid = 100
mail_debug = yes
mail_plugins = " quota"
mail_privileged_group = mail
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
passdb {
   driver = pam
}
plugin {
   quota = maildir:User quota
   quota_rule = ?:storage=4G
   quota_rule2 = Trash:storage=+100M
   quota_warning = storage=95%% quota-warning 95 %u
   quota_warning2 = storage=90%% quota-warning 90 %u
   quota_warning3 = storage=80%% quota-warning 80 %u
   sieve = ~/.dovecot.sieve
   sieve_dir = ~/
}
postmaster_address = postmaster at esrf.fr
protocols = imap pop3 lmtp sieve
service imap-login {
   inet_listener imap {
     port = 143
   }
   inet_listener imaps {
     port = 993
   }
}
service imap {
   process_limit = 2000
}
service managesieve-login {
   inet_listener sieve {
     port = 4190
   }
}
service pop3-login {
   inet_listener pop3 {
     port = 110
   }
   inet_listener pop3s {
     port = 995
   }
}
service quota-warning {
   executable = script /usr/local/bin/quota-warning.sh
   unix_listener quota-warning {
     user = dovecot
   }
   user = dovecot
}
ssl_cert = </etc/ssl/certs/dovecot.pem
ssl_key = </etc/ssl/private/dovecot.pem
userdb {
   driver = passwd
}
protocol lda {
   mail_plugins = " sieve"
}
protocol imap {
   imap_client_workarounds = tb-extra-mailbox-sep
   mail_plugins = " quota imap_quota"
}

Best Regards

-- 
________________________________________________________
Didier GERVAISE  didier.gervaise at esrf.fr  04 76 88 27 28
System Administrator       ----       Computing Services
ESRF    6 rue Jules Horowitz     38043 Grenoble Cedex 09
________________________________________________________