EXIM custom filter to block email address in name field?

I'm testing at this moment this exim filter: if $h_from matches "\"[^\">*@[^\">*\".*<(.*)>.*" then headers add "Old-Subject: $h_subject" headers remove "Subject" headers add "Subject: [False name] $h_old-subject (real email is $1)" headers remove "Old-Subject" endif
I'm getting a bad encoded new subject, when the real subject has non-US symbols. Someone knows how to fix this?