Channel richness is, in part, determined by the ability to facilitate rapid, two-way feedback. this means that an instant message will be richer than , because:

 this means that an instant message will be richer than an Email because we have
- The ability of the channel to handle multiple cues simultaneousl
- the ability of the channel to facilitate rapid, two-way feedback
and
- The ability of the channel to establish a personal focus for the communication 
On top of that, the development of smartphones make instant messaging much more simple and convenient compared to emails.