[Dovecot] strange regex sieve filter error

Hi all,

ok, I'm getting an error produced by the following sieve file :

require ["fileinto","copy"]; # rule:[SPAM-TAG] if allof ( header :regex "Subject" "^\\[SPAM-TAG\\]") { fileinto "SPAM-TAG"; stop; }

and I'm getting the following error in the dovecot delivery log :

main_script: line 3: error: unknown tagged argument ':regex' for the header test (reported only once at first occurence). main_script: error: validation failed.

But I looked up the syntax, and tried to figure out why this is getting the error. I guess I just don't quite know what this error means...

I know that the value that it is trying to match is kind of strange, but it is a regular expression, so it should work...

Thanks,

Tim.