In this example, we'll be using Microsoft Outlook, but the settings will be similar whichever email software you use. (We use and recommend Thunderbird from Mozilla)
1. Open MS Outlook and click Tools/E-mail accounts. Click Add a new e-mail account and click Next>
2. Choose POP3 and click Next>
3. Look at the screenshot below. In this example our website is called www.sagan.com and our email address is setup as carl@sagan.com. Carefully check your settings against these example ones>

Notes. Your Incoming mail server (POP3) is mail.yourdomain.com, NOT mail @ yourdomain.com
Your User Name is your entire email address, not just your name.
4. Your Outgoing mail server (SMTP) should be your Internet Service Provider's smtp server, below are some examples depending on your ISP:

4. Click the More Settings... button and on the Advanced tab, ensure that Leave a copy of message on the server is NOT ticked.
5. On this same tab, check that the Port numbers are 110 (incoming) and 25 (outgoing).
6. You are now ready to click Test Account Settings... you should get all ticks and then receive the test email.