2.11 Activation Framework
When JSM starts the Activation Framework default command map and default file type map are set using the mailcap.txt and filetype.txt files located in the system subdirectory.
SMTP/POP3, AS2/AS3 and HTTP services use the command map to encode and decode MIME content.
The HTTP content handlers, InboundFileHandler, OutboundFileHandler and OutboundMultiPartHandler use the file type map to associate filename extension to MIME type.