[Exim] Question

I have been looking trying to figure out how to masquerade the address of
the sender in the sender field. Example is as follows in case I am not
explaining this properly:

    user@??? be rewritten as user@???

I am sure this is documented somewhere, I just have not been able to find
it. Is this considered a filter?

Thanks in advance.


Stephen Malenshek
Valuelinx Corporation
stephen@???