Brosix is a secure instant messaging and collaboration tool featuring voice and video chat, unlimited file transfer, collaborative browsing, whiteboard, and screenshots and screen sharing. Interface includes tabbed chat, chat history, spell check and anti-virus support.
Messages with other Brosix users are secured and can be sent when they are offline and delivered upon return. All communication with other Brosix users is encrypted and clients are available for Mac, Linux, iOS, Android, as well as via a Web Client to use the Brosix network with most browsers.
Note that the program requires creating a login using an email address.