I have a mailbox that I use to send newletters to clients and it gets a lot of "System Administrator" Undeliverable messages since it sends out to a couple thousand recipients every two weeks. When I go into the mailbox (as an alternative mailbox in my Outlook setup) to delete them, Outlook freezes. If I set up the mailbox with it's own profile, it literally takes 30 minutes or more for a handful of messages to download to offline storage. Once they're downloaded to the .OST, I can click on them and delete them easily. Outlook Web Access displays the messages, but will not delete them. I have another mailbox that we use for a different, less frequent mailing and it has the same problem. In fact, I'm pretty sure System Administrator/Undeliverable messages will freeze for anyone. We're using Exchange 2003 from SBS 2003 for mail.

What happens if you attempt to view the mailbox through OWA? Simon.Simon Butler, Exchange MVP Blog | Exchange Resources | In the UK? Hire Me.

As I posted, I can view the messages in OWA, but I can't delete them.

When you try to delete them in OWA, what happens? Saying that you cannot delete them doesn't really help with diagnosing the issue. It is classic third party interference, AV or antispam would be my guess. Something choking on the special NDR format. Simon.Simon Butler, Exchange MVP Blog | Exchange Resources | In the UK? Hire Me.

Sorry for the delay it took a few days to do this. I upgrade Symantec Mail Security for Exchange on the server (uninstalling the previous version) and I'm still experiencing the problem. Our client machines aren't running Symantec; they're running Sophos which doesn't do jack with Outlook. Since OWA is also affected, this seems to be Exchange focused, not AV.

I operate a simple policy. Where Symantec's excuse for an AV product is installed on a server, that is the cause of whatever the problem is, until shown otherwise by its complete removal and a reboot of the server. Upgrading the product to the latest version hasn't really shown anything, other than the problem still exists with the new version. My recommendation would be to remove it, reboot the server and test again. Simon.Simon Butler, Exchange MVP Blog | Exchange Resources | In the UK? Hire Me.