Click "Tools", then "Accounts..."

 

Click "Mail", then your account, then "Properties".

 

For "Outgoing mail (SMTP)", please key in (without quotes) "smtp.mydomain-name.com". For example,
if your domain name is "signetique.com", you will key in "smtp.signetique.com".
At the "Outgoing Mail Server" section at the bottom, tick "My server requires authentication",
click "Settings..."