To set up mail account you need login to the CPanel and click on Mail Menu -> Add/Remove accounts -> Add Account. Then you need enter mailbox name you want, mailbox password and mailbox quota.

That is all. The mailbox is created. Now to use it you need set up your mailbox client correctly. THIS IS A MOST IMPORTANT STEP!!! Many CPanel users have troubles with it.

Remember please, your site has only ONE MAIN mailbox which is the same as your login name. This mailbox is created automatically duaring the domain installation process. To connect to this mailbox you need enter only mailbox name in the account name field in your mail client settings.

To conect to all other mailboxes you will create, you need enter mailbox name with domain name trailing by @ in the in the account name field in your mail client settings.

Here is example:
1. Your domain name is: perfectdomain.com
2. Your login is: perfect (so main mail account is perfect@perfectdomain.com)
3. You've created additional mailbox 'smit' in the CPanel.

So. To receive mail from main mailbox (perfect@perfectdomain.com) you need enter only perfect as account name in your mail client.

And to receive mail from additional mailbox you need enter smit@perfectdomain.com as account name in your mail client.

Hope this little explanation will help you to avoid one of the most popular mail problem in CPanel