You don't generally talk with pipe to daemons, instead, you communicate with them through socket. The IO::Socket is generally use as the basic building block for client-server communication, especially if the server is a custom beast, non-standard Internet server. If this is not the case, check CPAN if there's a module that provides client interface to your daemon.

The fact that you can do that with sendmail because it does provide the interface, doesn't mean it works generally for other daemons. You have to be exactly sure how your daemon works. What kind of daemon is it, by the way?