Mailbox Cleanup Pop-Up When Over Size Limit

[Jill Ferguson]

in Outlook 2002, when a user's mailbox reached it storage limit on the
Exchange Server, the mailbox cleanup dialog box popped up when they tried to
send a message. In Outlook 2003, this does not happen. The user just
receives an ndr from "System Administrator". Is there a way to get the
mailbox cleanup dialog box to pop-up by default?

We are running Exchange 2000 SP3 with Outlook 2003 SP3 clients on Windows
2000 SP4. We do have a group policy that turns off auto-archiving, if this
helps.

Thank you for your help.
-- Jill