Today's smartphones make it easy to check e-mail, so there's no excuse for having an overflowing inbox. But if you're just starting out as an entrepreneur, there's a good chance you're using a consumer-oriented "POP3"  e-mail service, which can become a headache as your business takes off. Here's why: Short for "Post Office Protocol 3," POP3 downloads messages to your device's e-mail client, such as Outlook or Entourage, and then deletes them from the server. So if you check messages from multiple devices--say, a laptop at home, a desktop in the office and a smartphone in between--each of their inboxes is different. It's more efficient to use an e-mail system based on Internet Message Access Protocol (IMAP), which keeps all of your devices' inboxes in sync by giving each one a copy of your messages but still preserving the original on the server. That means, for example, that you can read a message on your laptop in the morning and review it again in the afternoon from your smartphone. Ditto for messages you've sent, deleted or moved to a special folder, because every time one of your devices connects with the server, it gets an updated snapshot of your whole account. With POP3, you'd have to update each device individually and manually--a huge waste of time and a great way to get yourself in a position where an important message is on your desktop, but all you have is your smartphone. Not all e-mail providers charge extra for IMAP. For example, Google's free Gmail uses IMAP and works with most major e-mail apps, such as Outlook, Taroby and smartphone operating systems, such as Android, iPhone and Windows Mobile. Source: Entrepreneur.com