1. Open Mac Mail on your computer.

2. Click on 'Mail' top left, then 'Preferences'.

Mac Mail Preferences

3. Click on the 'Accounts' tab, then the '+' symbol bottom left to begin adding a new email account.

Mac Mail Accounts

4. Enter your full details into the screen that opens, then click 'Continue'. Don't worry if this then throws up a warning/error, just click 'Continue' again.

Add Account

5. On the next screen, on the 'Account Type' dropdown, select either IMAP (if you want emails to be available on multiple devices) or POP (if you want them to be removed from the server once Mac Mail has downloaded). Then enter a description for the account (it doesnt matter what you put for this, it is for reference), then the incoming mail server as mail.(yourfulldomain.com). Use your full email address for the username, and password. Click 'Continue'.

Incoming Settings

6. On the next window make sure that 'Use Secure Sockets Layer (SSL)' is unticked, and 'Authentication' is set to 'Password'.

Incoming Security

7. In this next window we will be defining the Outgoing Server Settings. Again the 'Description' is just for reference. 'Outoing Mail Server' will be mail.(yourfulldomain.com). Tick 'Use Only This Server'. Also tick 'Use Authentication' and enter your full email address for the 'Username' and your password. Click 'Continue'.

Outgoing Settings

8. On the next window make sure that 'Use Secure Sockets Layer (SSL)' is unticked, and 'Authentication' is set to 'Password'.

Outgoing Security

9. Confirm the details are correct in the final window. Make sure 'Take Account Online' is ticked and click 'Create'.

Account Summary
Note: Your server with Nimbus is capable of being used as a basic mail server, but the ongoing battle between spam management, hacking and blacklisting means that Office 365 and Google Apps are the go-to platforms if email is critical to your business/site. Read more here.