Internal Domain Forwarding Email messages sent internally within MailSite (i.e. domain to domain on the same server) receive special handling by the SMTPDA and do not travel outside the system. The advantages to this architecture are: - reduced costs (hardware) - increased performance - ensured message delivery - the highest levels of delivery security (for internal email) The disadvantage is: - any third party services that require internal email (i.e. domain to domain on the same server) to be sent externally and processed is not possible. MailSite does function with third party RFC compliant applications in sending external emails.