The Qpopper MIME Mangling (X-MANGLE) and Macro (MDEF) Extensions to POP3
This document describes two extensions to the POP protocol that have been supported for several years by some client and servers. One extension, X-MANGLE, allows clients to request that MIME body parts be removed or converted to a simpler format, that only selected headers be transmitted, and/or to for the message to be transcoded to a different character set. The other extension, X-MACRO, allows clients to define macros which are expanded when used, saving repetitive transmissions.