1. One or more computer readable storage media comprising program instructions stored thereon for facilitating document collaboration within a message environment that, when executed by a computing system, directs the computing system to at least: receive a request to send, on behalf of a sender, a message having an attachment; in response to the request, determine whether a collaboration option is selected in the message; if a determination is that the collaboration option is selected, then generate a collaborative version of the attachment at a location within the message environment associated with the sender and send the message to a plurality of designated recipients of the message with a reference to the collaborative version of the attachment; and if the determination is that the collaboration option is un-selected, then send the message to the plurality of designated recipients of the message with the attachment;