[Exim] Filter question

This is a rather stupid question, but I'm having a moment of major confusion.

Am I correct in asserting that this (domain changed to protect my customer) :

    if $header_to: contains "00@???"
    or $header_to: contains "01@???"
    then
      seen finish
    endif

does precisely nothing (exim 3.03) ?

Thanks,

Ceri Davies

--
I can please only one person per day. Today is not your day.
Tomorrow isn't looking good either.