If you have more than one computer or use a smartphone, you need a sync solution. When syncing is set up properly everything stays up to date on all your devices. For example, you can move a message to a folder on your phone and it is moved on all your computers also. Deleted messages and unread messages all look the same no matter where you look at them.
There are several solutions available with various costs and features. For most small businesses, we find that Google Apps for Business is the best solution. Give us a call and we can discuss the various benefits and features for your specific situation.