Stuff

protocol lda {
  # Address to use when sending rejection mails.
  postmaster_address = postmaster@localhost

  # Hostname to use in various parts of sent mails, eg. in Message-Id.
  # Default is the system's real hostname.
  hostname = fritzboxdeb

  # Support for dynamically loadable plugins. mail_plugins is a space separated
  # list of plugins to load.
  #mail_plugins =
  #mail_plugin_dir = /usr/lib/dovecot/modules/lda

  # Binary to use for sending mails.
  #sendmail_path = /usr/lib/sendmail

  # UNIX socket path to master authentication server to find users.
  auth_socket_path = /var/run/dovecot/auth-master

  # Enabling Sieve plugin for server-side mail filtering
  mail_plugins = cmusieve
}

auth default {
...
  ## dovecot-lda specific settings
  ##
  socket listen {
     master {
       path = /var/run/dovecot/auth-master
       mode = 0600
       user = mail # User running Dovecot LDA
       #group = mail # Or alternatively mode 0660 + LDA user in this group
     }
  }

}