To enable authentication for outgoing mail in Outlook Express:

Open Outlook Express

Select Accounts... from the Tools menu.

Accounts


Account Properties


Click on the imap.nw.uwplatt.edu account then click on the Properties button.


Imap account settings


Click on the Servers tab.

Server Settings


Check My server requires authentication under Outgoing Mail Server

(In Settings..., leave the default as Use the same settings as my incoming mail server)