protocol lda {
[...]
  postmaster_address = postmaster@cen05.xen.wbcd.pl
[...]
  # Support for dynamically loadable plugins. mail_plugins is a space separated
  # list of plugins to load.
  #mail_plugins =
  mail_plugins = sieve
[...]
}

[...]

plugin {
[...]
  # Sieve plugin (http://wiki.dovecot.org/LDA/Sieve) and ManageSieve service
  #
  # Location of the active script. When ManageSieve is used this is actually
  # a symlink pointing to the active script in the sieve storage directory.
  #sieve=~/.dovecot.sieve
  sieve=/home/vmail/%d/%n/.dovecot.sieve
  #
  # The path to the directory where the personal Sieve scripts are stored. For
  # ManageSieve this is where the uploaded scripts are stored.
  #sieve_dir=~/sieve
  sieve_dir=/home/vmail/%d/%n/sieve
}

protocol lda {
  # Space separated list of plugins to load (default is global mail_plugins).
  mail_plugins = sieve
}

protocol lmtp {
  # Space separated list of plugins to load (default is global mail_plugins).
  mail_plugins = sieve
}

##
## SIEVE specific settings
##
plugin {
  # The path to the user's main active script.
  # usually this means $HOME/.dovecot.sieve (/home/user/.dovecot.sieve)
  #sieve = ~/.dovecot.sieve
  sieve=/home/vmail/%d/%n/.dovecot.sieve

  # A path to a global sieve script file, which gets executed ONLY
  # if user's private Sieve script doesn't exist. Be sure to
  # pre-compile this script manually using the sievec command line
  # tool.
  #sieve_global_path = /var/lib/dovecot/sieve/default.sieve
  # optionally - but not needed
  # mkdir -p /var/lib/dovecot/sieve
  # touch /var/lib/dovecot/sieve/default.sieve
  #sieve_global_path = /var/lib/dovecot/sieve/default.sieve

  # Directory for :personal include scripts for the include extension.
  #sieve_dir = ~/sieve
  sieve_dir=/home/vmail/%d/%n/sieve

  # Directory for :global include scripts for the include extension.
  #sieve_global_dir =
  # optionally - but not needed
  # mkdir -p /var/lib/dovecot/sieve/default.sieve
  #sieve_global_dir = /var/lib/dovecot/sieve/global/
}