[Exim] demand dial exim

Howdi

Im running exim-4.01 on a redhat 7.2 server...

have the following problem, the server sits on a corporate network with
an ISDN connection which
is setup for demand dialup.

Everytime that someone sends a message to the server it dials up...
So basically when it going through the smtp transaction and
gets to

rcpt to:<mail@???> this is the point where the box dials....

Anyone know how I can stop this ??? I want to be able to queue
everything for an hour then
send it out one shot ...

I know this is an easy question, in sendmail you use somehthing like
FEATURE(`accept_unresolvable_domains')dnl

Thanks

Chris