[exim] limiting mail sending rate

Hi
Is there a way to limit the rate at which exim sends outgoing mail ,
i have a client that has a problem when he sends mail to his
marketing lists, his upstream isp limits the number of messages he can
send per hour ... So I would like to be able to setup the server to
spool all the mail for delivery then send the mails at a limited rate eg
10 / minute , thus all the mails go out and non are bounced by
the isp .... But I need this to only apply to a limited number of
addresses, cause if a users sends a mail and its qued with the marketing
mail it will be delayed for to long ... any examples / howto's on this
.. so far haven't seen it on the faq ..

Greg