If you want one (or more) email address on your domain, ClusterCS offers an easy way to setup it.
Start by navigating to the Email tab of your domain:
On the Add Email form, you have to set up an email address and a password. The extra options include setting a fixed Inbox size for the email address.
You can also set aliases (In the case of the picture below any mail sent to aliasexample[at]example[dot]org will be sent to this inbox – example[at]example[dot]org) and forwards (In this case all mails sent to example[at]example[dot]org will be also sent to example[at]clustercs[dot]org.
Remember to press Enter after entering each alias/forward email in order to save it.
Now, you probably want to set an e-mail client for your new e-mail address.
For Outlook, the settings should be as follows (Replace user.example.org with your own domain):
Fill in your Account information for Incoming / Outgoing mail :
Incoming IMAP Port: 143
Outgoing SMTP Port: 587
Enter your password and Connect to your account: