KB 258
From SWCP Support Wiki
Get Outlook Express not to leave mail on the server
Article:258 Created:2003-10-20 18:02:19 Categories: E-mail
Question or Symptom
If Outlook Express is configured to leave your mail messages on the server, your mailbox will overflow. Here's how to fix it.
Resolution
Start Outlook Express.
Click on Tools, then Accounts, then the Mail tab.
Select the "mail.swcp.com" entry to highlight, then click Properties Button
Select the Advanced tab, and remove the check mark from each item which says "leave copy of messages on server".