To Setup Authenticated SMTP with Outlook 2003 first open outlook, then on the menubar find tools then click on email accounts as shown in Figure 1.

Figure 1

you should then see a window appear select view or change existing as in figure 2

Figure 2

Select Next and a window like Figure 3 should appear.

Verify your settings here and click on more settings on Figure 4 you should select my outgoing server (SMTP) requires Authentication

then select Log on using and enter your email address and password select remember password if you wish to have outlook not prompt you for it on each send.