Problem: You are a linode user, or your host provider does not ship with a mail server, and you don't want to or don't know how to set up a mail server. Google app mail is will be a good, free and quick way.

How?
Considering you can easily find lots of step by step guides, I am posting my dns settings for you as reference:

Essentially, you will be going through these steps:

• Open/activate an Google app account, provide necessary personal and domain information.
• Go to the DNS manager inside Linode, or make according changes (adding CNAME, MX records) on your own DNS settings. You don't have to add a new CNAME, it can be accessed with https://mail.google.com/a/your-domain-name.com
• It may take a few hours to get your DNS records updated, depends on your settings. You will then need to verify your domain ownership by either modifying the dns record or creating a new html page.

Sounds simple? It is that simple.