Run Outlook, then click Account Settings under the Tools menu item.
On the Account Settings window, select the email account you want to examine (in most cases, only one will be listed), then click the Change ... button.
On the Change E-mail Account window, make sure that the value for the User Name field reflects your full email address (i.e., "firstname.lastname@example.org", not just "example" [without quotes]). Next, click the More Settings ... button near the bottom right corner of this window.
NOTE: Likewise, if you are adding a new account, you would see a similar screen after you clicked New ... (instead of Change ...) button on the above (two steps previous) Account Settings window.
On the Internet E-mail Settings window that is now displayed after you have clicked the foregoing More Settings ... button, click the Outgoing Server tab. Make sure that the box is checked for "My outgoing server (SMTP) requires authentication" and that the radio button for "Use same settings as my incoming mail server" is selected.
Now you need to click the Advanced tab on the same Internet E-mail Settings window.
In the field for Outgoing server (SMTP), there will be a number. If that number is 80, you need to change it. Acceptable numbers are 25 (the default) or 587. After changing this, try sending a test email message. If you are unable to send mail now, try a different number. Not all of those will work for all customers, which is why we give you both options. If you have tried both and are still unable to send out mail, please call EONI Technical Support for assistance, as there may be another problem.
Now you can click OK. You are now finished applying your settings, and could do a trial message send as a test.