Presumably the .filter file generated from the CPanel frontend can be editted by hand (via SSH) and can contain any Exim filters, not just the $header_contains etc. that the frontend allow?

E.g. can we use $reply_address, $header_resent_from, $header_Content-Type etc?

Also, is it safe to use "user@domain.com" without escaping the @ - sorry, I'm more used to procmail.....

Or is the .filter file not actually an Exim filter but some weird CPanel thing?