From Lunarpages Web Hosting Wiki
How can I enable IMAP on my web hosting account?
IMAP (Internet Message Access Protocol) is a mail protocol that syncs a person's mail program with the corresponding account on a specific mail server. It is one of the two most popular protocols for e-mail retrieval. Most modern e-mail clients these days support IMAP configurations for your e-mail accounts.
How does IMAP e-mail work?
For an example, let's say I wanted to keep my e-mail on my desktop PC via my e-mail client, however, when I was away from the PC, I wanted to be able to access that same e-mail setup via a webmail interface or from your smart phone. IMAP makes that possible. Your e-mail is stored on the server, and your webmail and desktop client can both interface with it.
Here is an image showing how the relationship works.
As you can see, any changes you make on either side is reflected on the server. So if you moved an e-mail to a folder from your desktop machine, it would be moved the next time you login to your e-mail via your webmail client.
There are no extra steps to take to enable this feature on your hosting account. All you need to do is put in the correct setting into your e-mail client of choice. Your e-mail settings are in your account information (or Welcome e-mail) you received when your account was created.
You can review this information by logging into the Customer Account Page here: https://account.lunarpages.com
Click on Hosting Information and then scroll down to Email Instructions. Now setup your desktop e-mail client to use IMAP, instead of POP3 when setting up your e-mail address in the program and you are ready to use IMAP to keep your e-mail in sync.