[Exim] relaying - for dialup user

Hi

How can I set it up so that a user on dial-up (dynamically assigned IP from
DHCP server upon dialup) can relay through a server of mine ?

--
salvo@??? | ICQ # 8084066

Only one creature could have duplicated the expressions on their faces, and
that would be a pigeon who has heard not only that Lord Nelson has got down
off his column but has also been seen buying a 12-bore repeater and a box
of cartridges.
        -- (Terry Pratchett, Mort)