MIME type name: application (If the above is not an existing top-level MIME type, please explain why an existing type cannot be used.) MIME subtype name: activemessage Required parameters: none Optional parameters: none Encoding considerations: Currently, the content of the activemessage subtype is of the form: where is an internet host name or number and could be any alphanumeric string. The effect of "opening" the activemessage is that the user becomes connected to the Active Mail application residing on host . Security considerations: An application identifier is similar to a password to enter a particular Active Mail application (such as a conversation, document, etc.) running on host . It is up to the user/application to choose public (well known) names, for openly accessible applications, or sparse names for private applications, as well as to protect the names known to them. Active Mail can incorporate more sophisticated security mechanisms, based on public keys, but they are not being planned at present.