Entourage is a program developed by Microsoft that offers many tools to effectively manage email on a Mac in a more streamlined way. Not only can you flag email, creating email categories and views are other ways to index the inbox.
I was completely impressed with this program that uses automatic filters to perform many of the mundane actions that tie up your time. Another feature that you may find helpful is the automatic linking of messages to replies or parent messages, with the option to link other items as well; such as calendar items, to-do lists and projects.
Entourage 2008 allows you to use Microsoft Word as an email editor. Coming from Microsoft, I fully expected it to collaborate with other Microsoft products such as Word and MSN instant messenger. What I didn’t expect was for the program to be so incredibly slow and annoying at times. The interface takes forever to load and searching the folders can be classified as a nightmare.