From: To: Subject: multipart/alternative MIME-Version: 1.0 Content-type: multipart/alternative; boundary="boundary" MIME alternative sample body (user never sees this portion of the message) These messages are used to send multiple versions of the same message in different formats. User-agent will decide which to display. --boundary Content-type: text/html HTML version
HTML version
--boundary Content-type: text/plain Text version --boundary--