Abstract: The present invention relates to display systems mountable on posts, and more particularly to media display systems mountable on posts in general, and on posts including mailboxes as part of or attached to posts. A modular mounting system is provided which enables the fast, secure and easily changeable mounting of a display system to a mounting structure, where a support is on a post (which could include a mailbox) having easily attachable cooperating mounting structure on the post and the display. A mounting system is provided to display media from a support structure using a bracket and interface assembly. In a preferred embodiment, the mounting system allows for a media display to connect directly to the bracket and interface assembly via a sleeve.