Pop3 service stops responding

[Mike Eriksson]

Hi!

I have problem with the pop3 service stops responding at random intervals
on my server. We started to notice this problem as we're running icinga to
check the imap & pop3 service.

When icinga reports that the service is down. We try to telnet to the
server on port 110 but it refuses the connection.

I've checked the netstat during this time and it's listens on port 110. My
first thought we were hitting the max connections and similar.

Changed login_max_connections from 128 to 256. Didnt solve the problem.

Started the debug on the dovecot server but could not see anything in the
logs. Also the error log or the syslog dosnt report anything that I can see.

Best thing would of course be to start and upgrade the software and
os(Debian 5) but I'm not comfortable upgrading it at the moment as my
knowledge about dovecot / postfix isn't great.

Do you have any idéas how to move forward?

dovecot -n
# 1.0.15: /etc/dovecot/dovecot.conf
base_dir: /var/run/dovecot/
log_path: /var/log/dovecot-error.log
info_log_path: /var/log/dovecot-info.log
log_timestamp: %Y-%m-%d %H:%M:%S
protocols: pop3 imap imaps pop3s
ssl_cipher_list: ALL:!LOW
disable_plaintext_auth: no
login_dir: /var/run/dovecot//login
login_executable(default): /usr/lib/dovecot/imap-login
login_executable(imap): /usr/lib/dovecot/imap-login
login_executable(pop3): /usr/lib/dovecot/pop3-login
login_max_processes_count: 256
first_valid_uid: 1090
last_valid_uid: 1090
first_valid_gid: 1090
last_valid_gid: 1090
mail_privileged_group: mail
mail_location: maildir:~/Maildir
mail_executable(default): /usr/lib/dovecot/imap
mail_executable(imap): /usr/lib/dovecot/imap
mail_executable(pop3): /usr/lib/dovecot/pop3
mail_plugins(default): quota imap_quota
mail_plugins(imap): quota imap_quota
mail_plugins(pop3): quota
mail_plugin_dir(default): /usr/lib/dovecot/modules/imap
mail_plugin_dir(imap): /usr/lib/dovecot/modules/imap
mail_plugin_dir(pop3): /usr/lib/dovecot/modules/pop3
pop3_uidl_format(default):
pop3_uidl_format(imap):
pop3_uidl_format(pop3): %08Xu%08Xv
auth default:
  username_chars:
abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ01234567890.-_@%
  username_translation: %@
  username_format: %Lu
  passdb:
    driver: sql
    args: /etc/dovecot/dovecot-sql.conf
  userdb:
    driver: passwd
  userdb:
    driver: sql
    args: /etc/dovecot/dovecot-sql.conf
  socket:
    type: listen
    client:
      path: /var/spool/postfix/private/auth
      mode: 432
      user: postfix
      group: postfix
    master:
      path: /var/run/dovecot/auth-master
      mode: 384
      user: vmail
      group: vmail
plugin:
  quota: maildir
  sieve_global_path: /etc/dovecot/sieve_scripts/spam-sort.sieve

login_max_processes_count: 256
login_max_connections: 256
max_mail_processes: 1024

Best Regards
Mike