One way to make your email inbox a little easier to manage is by color coding your emails. This can be done in one form or another in just about every email platform including Lotus Notes, Microsoft Outlook, and GMail. I typically suggest no more than four colors, otherwise all the colors in your inbox may give you a headache which would be counterproductive. I suggest a color for each of the top three or four categories of emails in your inbox. Mine happen to be red for customer emails (higher priority), blue for internal work related emails, green for personal and black for everything else.
In GMail, you would use "Labels" to color code the emails and "Filters" to automatically apply the labels to incoming emails.
In Lotus Notes, you can choose three colors. These colors can be automatically assigned to each matching email by clicking on the Tools menu, then Preferences, then the Message Marking tab.
In Outlook, you can color code emails by clicking on the Tools menu, then Organize, then Using Colors on the left of the organize area.
Color coding emails in this way will allow you to quickly prioritize your emails at a glance. In my seminars, I suggest only checking emails twice per day because of the time it takes to refocus each time an email interrupts your train of thought. If you work in an industry where responsiveness is paramount, however, color coding your emails will allow you to quickly respond to customer emails while putting off vendor emails until the end of the day.