Outlook Express: Open Outlook Express > Extra > Accounts > E-Mail Tab > Eigenschappen> en servers tab check the checkbox next to "My Server Requires Authentication"
Click Ok > Click Close

Outlook Open Outlook > Click Tools > E-Mail Accounts > View or change existing e-mail accounts
Select the email account > Click Change > Click 'More Settings' > Click the 'Outgoing Server' Tab
Check the checkbox "My outgoing server (SMTP) requires authentication"
Click OK > Next > Finish
