1. A system for secure collaboration and communication, the system comprising: one or more computing resources at a service provider implementing a collaboration service, wherein the one or more computing resources include non-transitory computer-readable storage medium having computer-executable instructions stored thereupon which, when executed by a computer, cause the one or more computing resources to: receive a posting request from a user associated with a first computing device to post content without specified recipients to a collaboration channel provided by the collaboration service, the posting request initiated by user input dragging the content onto a graphical drop target within a graphical user interface associated with the first computing device, the collaboration channel allowing discussion by authorized users within a trusted network about the content; receive from the first computing device comments of the user affiliated with the posting request; determine, based at least in part on the posting request, whether a location of the first computing device is in the trusted network; attempt to authenticate the user to determine an identity of the user; identify a set of the collaboration channels to which the user is authorized to post the content based, at least in part, on a context for the post, the context comprising the location of the first computing device as internal or external to the trusted network and the identity of the user as authenticated or non-authenticated; in response to the location of the first computing device being external to the trusted network and the identity of the user being non-authenticated, and based at least in part on the content of the post, identify one or more collaboration channels from among the set of the collaboration channels in which the user is authorized to post the content; cause to be displayed in the graphical user interface of the first computing device options for selecting among the one or more collaboration channels in which to post the content; receive a selection through the graphical user interface of at least one collaboration channel of the one or more collaboration channels; aggregate the content with any previously posted content substantially similar to the content in the at least one collaboration channel; and notify an authorized user of the at least one collaboration channel within the trusted network about the content being posted by a non-authenticated user external to the trusted network; receive a different posting request from a second computing device of a second user to post different content; in response to the location of the second computing device being internal to the trusted network and the identity of the second user being authenticated, and based at least in part on the different content, identify one or more different collaboration channels in which the different user is authorized to post the different content, wherein the different content has first access rights defining authorized users permitted to view the different content, and wherein the one or more different collaboration channels are identified based, at least in part, on the first access rights; and receive comments of the second user affiliated with the different content, the comments having second access rights defining one or more of the authorized users permitted to view the comments, wherein the first access rights of the different content are different from the second access rights of the comments.