Webmail Forwarding Basics
From Lunarpages Web Hosting Wiki
Q: In Cpanel, I have an email address which is forwarded to a gmail account that currently has 6 MB of e-mail but the 'inbox' on Lunarpages for the same account is 150 MB. How can this be? This makes me think that even deleting messages within gmail still doesn't delete them from the mail file on my Lunarpages server.
A: First of all, I think I should explain about setting up mail forwarding since this is where most of the problems you've experience have stemmed from. When you set up an e-mail forwarder in Cpanel on your Lunarpages account, you do not have to create a corresponding email address.
If you do set up an e-mail address under Add/Remove email accounts but also set it up to forward to a different address, you will have mail saved on the Lunarpages server at the same time as having it forwarded to a different email account such as a gmail account or a Yahoo account. In this case, even if you delete your received email on the gmail or Yahoo account, your email on the Lunarpages server will remain intact because it is a separate account. You will need to explicitly logon to your Lunarpages account on the server and delete the accumulated emails which are taking up space. Some people actually prefer this method.
However, if all you need is to have an email address under your domain which forwards to an existing email address somewhere else, all you need to do is set up a Forwarder - you do not have to also create an account on the server by going through Add/Remove Accounts. So, if you currently have both a forwarder and an account created under Add/Remove Accounts, you should be able to go through Add/Remove Accounts and remove that particular account so that it does not continue to take up space on the server through accumulated emails.
Some people however, do not like keeping their email on a web server. They like to download the email to their own machine's hard disk so that they will have access to the email even if they are offline. This is usually called "downloading your email". You can retain a copy on your hard disk by using an email client like Outlook, Outlook Express or Eudora which can download a permanent copy of the email to your hard disk via POP3.