In this tutorial, we'll be going over how to set up your email account in an email client. The settings will be the same for any email client. In this tutorial, we'll be using Apple Mail (my favorite).
Keep in mind, you can always view your email from any machine on the internet by going to https://shellsurf.com/mail.
Here we go!
Open up Apple Mail.
If this is your first time opening it up, you'll be prompted with the "New Account" screen, skip to the new account step.
If you've been in Apple Mail before, you may not get that screen. To get there, go to "Mail -> Preferences".

Click the plus sign in the lower-left corner.
Skip to the general information step.

On the "New Account" screen, click the "Continue" button.

Select "POP" as the account type.
Enter your name and email address.
Click the "Continue" button.

For the incoming mail server, enter your domain name (without the "www" prefix).
Enter your username and password.
Click the "Continue" button.

For the outgoing mail server, enter your domain name (without the "www" prefix).
Check the "Use Authentication" checkbox and enter your username and password.
Click the "Continue" button.

At this point, you'll probably get an error (like below). It's OK. We force a secure connection to ensure your privacy, and that information has not been entered yet.
Just go ahead and click the "Continue" button, we'll enter the security info in a bit.

Check the "Use Secure Sockets Layer (SSL)" checkbox.
Select "Password" for the authentication.
Click the "Continue" button.

Check over all the summary info.
Click the "Continue" button.

Click the "Done" button.

Back on the Preferences window, under "Accounts", your new account should be selected and you should see the settings you just entered.
The "Account Information" tab should be selected (select it if it's not).
Under "Outgoing Mail Server (SMTP)", click the "Server Settings..." button.

Make sure your domain is entered as the outgoing mail server.
Check the "Use Secure Sockets Layer (SSL)" checkbox and change the server port to 465.
Select "Password" as the authentication and enter your username and password.
Click the "OK" button.

Select the "Advanced" tab.
Check the "Use SSL" checkbox and change the server port to 995.
Select "Password" as the authentication.

Close the Preferences window by clicking the red dot in the top-left corner.
Click the "Save" button to save your changes.

That's it. You should now be able to send and receive email. One thing to note: you may be shown a warning when you send or receive mail, such as the following:

Go ahead and click "Yes" to continue using the server.
What this means is that the security certificate that is being used to secure your email coming in and going out is not verified by a third party. That doesn't mean it doesn't work, just that a third party has not been paid to verify that it works.