The Mail client in Mac OS X Leopard includes a new option in Preferences > Accounts > Advanced called "Use IDLE command if the server supports it". But it does not work for me. New mail only arrives if I explicitly check or if Mail periodically checks. Judging from other posts on this forum, the feature doesn't seem to be working for anyone else, either. I would just like to know... Has anyone actually gotten this feature to work at all?