Cron postie wordpress

Postie has an admin function that lets you check to see if new mail has arrived- this has to be done before the email gets posted to the wordpress blog- but they suggest setting up a cron job to do it. I have managed to do this with both curl and wget. The trouble is that when the cron job runs, formatting, which displays fine when the mail is called from within Postie, is removed! I thought the cron job was doing exactly what Postie was doing when I manually check the mail. Anyone have an idea of what it could be?