I don't think this is possible using the simple agents. However, you can use a bit of formula language to preserve the original senders name:
thisfrom := From;
FIELD ReplyTo := ReplyTo;
@SetField("ReplyTo"; thisfrom);
REM 'This bit is to stop recursive mail if you are sychronising two mail files';
thisto := @If(@LowerCase(SMTPOriginator) != "name@company.co.uk"; "name@company.co.uk"; SendTo);
FIELD SendTo := SendTo;
@SetField("SendTo"; thisto);
@If(thisto = "name@company.co.uk"; @MailSend;""
You will also need to add a line couple of lines of code that:
a) add a flag to the document to indicate it has been forwarded and
b) a check to see if this flag has been applied.
if you don't add and check for this flag and you run the code above 'as is' after new mail arrives, it will constantly send each mail message again when a new one arrives. The good news is that R6 has some built in flags so you don't have to write the initial flag to the document.