Ad based services such as Gmail and Yahoo Mail scan your email to determine "keywords" or advertising opportunities. This information is cataloged, stored and over time used to build your personal profile. Information about websites you've visited, search queries you've made and information scanned from your emails is some of the information stored in these personal profiles. Google and others sell your information you have provided them about yourself by using their "free" services. Here are just some examples of how your information is sold to advertisers.
Dibz will never sell, scan, catalog or keep any kind of information about your email and web activity. It's none of our business. Make it your business to protect yourself!