MailJet is a "newsletter software" (also called "maillist software"), used to send customized emails to a list of recipients. MailJet is a direct marketing software, which can be used to send out press-releases, newsletters and announcements to your customers, subscribers and partners. MailJet comes with a built-in contact list manager and allows sending personalized emails by using tags. All you have to do to start your first bulk email marketing campaign, is to copy you email-account settings from your email software and start sending out messages in seconds.
MailJet is shareware, you can free download and try it for free during trial period. After that you may buy it for $30.95 or should delete it.