Internet Direct (Indy) Version 9.0.2 Beta
TIdMessage.AttachmentEncoding
Identifies the default encoding mechanism used for message parts.

property AttachmentEncoding: string;
Description
AttachmentEncoding is a String property that identifies the encoding mechanism used for attachment message parts in the message. Changing the value of AttachmentEncoding for the message also updates the default encoding used for all message parts in the message.