Outlook 2003 Mailbox Cleanup
Do you know how big your mailbox is? What is the default size limit of an Outlook/Exchange mailbox? How much e-mail are you storing? What happens when you're near the limit? It is important to understand the answers to these questions so you aren't prevented from sending and/or receiving e-mail.
The default mailbox size limit is 150 MB. As you reach your limit, you'll get a message about the possibility of being unable to send or receive messages (when approaching ~140 MB). Don't panic, with these first warnings you are still fully able to send and receive email messages. However, if you don't do some cleanup you'll eventually receive some more warnings about not being able to send messages (when approaching ~145 MB). Finally, if you still don't clean up your mailbox, you'll eventually be unable to receive messages at all (once limit is reached @150 MB).
Download Instructions Here (word) (pdf)
Portion of the texts extracted from the following Stanford University web site http://www2.slac.stanford.edu/comp/messaging/faq/