Redmine

according to the page,

http://www.redmine.org/projects/redmine/wiki/RedmineReceivingEmails
where I can read

Redmine has a feature that provides the ability to accept incoming emails from unknown users. In order to use this feature, an extra parameter has to be included:

I did this

./rdm-mailhandler.rb --url=https://lab.domain.net --key=secret --unknown_user accept --no-permission-check --project=foo

and I get this error:

./rdm-mailhandler.rb: unrecognized option `--unknown_user'
/usr/lib/ruby/1.8/getoptlong.rb:403:in `set_error': unrecognized option `--unknown_user' (GetoptLong::InvalidOption)

the question is.. what I am doing wrong?

thanks in advance