Microsoft Outlook 98

Open Outlook.
Select Tools > Services... from the menu at the top of the screen.
The Services window will appear on the screen. If it's not already selected, select the tab that says Services.
Select Internet E-mail from the area labeled The following information services are available, and click the Properties button.
The Properties window should appear. Click on the Servers tab.
Near the bottom of the Properties page in the section labeled Outgoing Mail Server, make sure the checkbox next to the words My server requires authentication is checked.
Click the Settings... button directly to the right of the words My server requires authentication.
The Outgoing Mail Server window should appear. At the top of this page is a circular radio button with the words Use same settings as my incoming mail server. Make sure this circle is selected and then click OK at the bottom of the page.
You will be returned to the Properties window. Click the OK button at the bottom of the page.
You will be returned to the Services window. Click OK at the bottom of the screen.