Similar to Outlook XP, Outlook Express 6.0 has a security feature that can alert you if other programs are trying to send E-mail through Outlook. When this happens, you will receive the following message for each message you try to send.
This warning screen will appear if the "Warn me when other applications try to send mail as me" feature is selected in the security options.
To disable this warning, click Tools menu in Outlook Express 6.0 and choose Options. Select the Security tab and, under the Virus Protection section, clear the Warn me when other applications try to send mail as me option. Click Apply and OK.