Click "Next" after selected "View or change existing e-mail accounts"

The email accounts that configured in your Outlook will be listed.
Select the problematic email account and click on "Change" button

Verify your Incoming and Outgoing mail server name is correct.
Verify you have full email address on your Account Name with correct password. After that, click on "More Setting" button..

On the "Outgoing Server" tab, check the "My outgoing server (SMTP) requires authentication"

On the "Advanced" tab, change default Outgoing server (SMTP) port from 25 to 26

Click OK and save your changes, restart your Outlook to test on send/receive message.