MailingBoss in an autoresponder, developed by Builderalls CTO. It is an automation capable system that allows the RPM System to connect email sequences, and campaigns automagically, so you never have to edit or manually send email to your subscribers. Mailingboss has unlimited emails available when using the Builderall premium account. 
Mailingboss, contains your list that are connected to the RPM System email sequences. Its tagging system is what allows complete automation of the RPM System, and no other platform has this technology.