<p>A message is received from a content provider. A selection of one or more files is received from the content provider. A page specification is received from a first entity, the page specification indicating one or more assets to be displayed in a message interface. The page specification further specifies the placement of the one or more assets in the message interface. The page specification further specifies that at least one of the assets to be displayed in the message interface is to be selected by the content provider. A message interface is generated based on the page specification. The message and a set of links to the one or more files are displayed in the message interface.</p>
