Editing MAPI (section)

== Incompatibility with Internet Mail ==
The [[Simple Mail Transfer Protocol]] has always supported the concept of mail with multiple authors, and distinguishes between the "sender" and "authors" whenever there is more than one of the latter. MAPI cannot represent separate authors and senders except through the delegation mechanism, which does not permit more than one author.  Thus MAPI cannot accurately transmit group letters from scientific communities to legislators, or presentation of group research via email, or similar scenarios.  When fully SMTP compliant mailers (e.g. [[Mozilla_Thunderbird|Thunderbird]]) send perfectly formed SMTP messages with multiple authors into MAPI-dependent email infrastructures (such as Exchange/Outlook, O365, or Outlook.com) the messages must have their information density reduced to fit MAPI, presenting challenges for authentication and anti-spoofing technologies that rely on accurate message metadata transmission, and fundamentally changing messages to be something other than what was originally sent. Although the security implications impact all users, inability to represent multiple authorship is generally of little concern in purely hierarchical settings such as traditional businesses and military organizations, primarily impacting legislative and academic institutions.