To make eM look a lot nicer it would be great to be able to customize the way it looks to a user liking, for instance I’d REALLY like to have nicer hi-res icon commands on the toolbars above , a lot like Incredimail had/has. 
Hi, the only way how to customize eM client is to change between themes. In this version we will most likely not make any change into this.
I have heard something about next version that it will be reworked, but this is not supposed to be taken as confirmation.
Jan