courier-imapd or dovecot services cannot be started: Address already in use

Symptoms

• Cannot start courier-imapd service:

  # service courier-imapd start
  courier-imapd: bind: Address already in use

  OR

  Cannot start Dovecot service:

  # service dovecot start
  Starting Dovecot Imap: Error: service(pop3-login): listen(*, 110) failed: Address already in use
  Error: service(pop3-login): listen(*, 995) failed: Address already in use
  Error: service(imap-login): listen(*, 143) failed: Address already in use
  Error: service(imap-login): listen(*, 993) failed: Address already in use
  Fatal: Failed to start listeners
  [FAILED]

• There is a process binding the ports required by Dovecot or Courier:

  # lsof -i :110 -i :143 -i :993 -i :995
  COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
  portreserve 348 root 25u IPv4 591668177 0t0 TCP *:pop3 (LISTEN)

Cause

The ports required by Dovecot or Courier are being used by another process.

Resolution

1. Connect to the server via SSH

2. Kill the processes binding on the required ports:

   # for PID in `lsof -i :110 -i :143 -i :993 -i :995 | egrep LISTEN | awk '{print $2}' | uniq`; do kill -9 $PID; done

3. Start Courier or Dovecot service:

   • Courier:

     # service courier-imapd restart

   • Dovecot

     # service dovecot restart

4. In case the PortReserve was the process binding the required ports, disable it with the following commands:

   • For SysVinit:

     # service portreserve stop
     # chkconfig portreserve off

   • For Systemd:

     # systemctl stop portreserve
     # systemctl disable portreserve