Postfix - fetching mail periodically on a dial-up

I am using postfix on SuSE 8.1 with a dial-up connection. At present when I go online it sends and fetches mail. I can then cause mail to be sent with 'sendmail -q' and I have found some info on automating this. What I haven't been able to do is find info on getting the fetching of mail to happen periodically (say every 5 or 10 minutes) as long as I am connected. How would I set this up? Thanks. -- Steve Crane http://craniac.afraid.org