The challenge I have, which may not be shared by many people, is that I have many email addresses for each domain I'm working with, and I'm working with 3-5 domains at a time. 

One of the reasons I LOVE Zoho is I can collect all of my email in one place, and this feature alone rocked my world. 

What would be truly extraordinary is if I could select different colors for each email tab. That way I could group all of my emails with one domain in red, for example, and another domain with green. If there were shades of each color, I could use dark shades for high priority accounts like sales@ and lighter shades for lower priority accounts like webmaster@