QK SMTP Server is a powerful but easy-to-use smtp server software, which can send mails from local host to the recipients' mailboxes directly at an amazingly high speed. Arrived or not, you will get feedback instantly.
The new version of QK has got a function which very similar
to what you've said. E.g.: You can choose a certain group
"invalid recipients" to send mails to this single
group.
