you have two options ( maybe more I don't know :)
if you don't mind a few pop up's then you can use outlook to send your mails and this saves you having to set up the email servers etc but if you want to do more then you can use sendmail
sendmail tutorial
outlook can be used in a few ways but causes a prompt to check if you want to allow another application to send mail on your behalf although you can work around this partially by opening the message then using sendkeys to send ' Alt+s ' although this will cause a brief flicker on the screen and could potentially go wrong if the message is not on screen when sending the keys.
you can also buy code that bypasses this but that depends on whether you want to spend the cash
sorry, I am not sure how this translates to vb6! as have just realised you stated vb6 <:)