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.
This response is sent when the SMTP server incurred an error in processing an SMTP transaction
QK SMTP Server can work
with most mail clients, including Outlook Express,
Eudora, IncrediMail, the Bat!, Mutt, KMail, Pegasus, DevMail,
Mail Bomber, Delta Mail, Foxmail, and more! QK SMTP
Server can also work with most mass email sender software
so as to improve their performance in an amazingly way!