Problem solved. I put the List in the session object, then I put an instance of Bulletin in the command object. My code now looks like this.
List<Bulletin> bulletins = bulletinDAO.getApprovedBulletins();
mav.setViewName("EnterBulletin");
if (bulletins != null) {
ServletRequestAttributes attributes =
(ServletRequestAttributes) RequestContextHolder.currentRequestAttributes();
HttpSession session = attributes.getRequest().getSession(true);
session.setAttribute("bulletins", bulletins);
mav.addObject("command", new Bulletin());
}