Autoresponder adds "on behalf of"

When I set up an autoresponder for [email protected] the autoresponder gets sent, but in the FROM it says [email protected]; on behalf of; Equipo XtraClase.Com [[email protected]]

Is there a way to prevent the "on behalf of" ?

 

Nevermind, just found it. In Exim Configuration, just uncheck "Set the Sender: Header when the mail sender changes the sender (-f flag passed to sendmail)."