Some mail servers limit
emails one IP address can send during an amount of
time. To cope with this, KMailer introduces a special
delivery mode which can periodically slow down KMailer's
fast email sending in order to allow slow Mail Servers
to "catch their breath."
This optional feature can help avoid overloading
the slow mail servers and improve the sending success
ratio dramatically. And KMailer is the ONLY bulk email
software with this feature at the present time.