- Don't give your email address out arbitrarily
Email addresses have become so common that a space for them is often included on any form that asks for your address.
- Check privacy policies
- Be aware of options selected by default
When you sign up for some online accounts or services, there may be a section that provides you with the option to receive email about other products and services. Make sure to change the settings.
- Use filters
Many email programs offer filtering capabilities that allow you to block certain addresses or to only allow email from addresses on your contact list.
- Report messages as spam
Reporting messages as spam or junk helps to train the mail filter so that the messages aren't delivered to your inbox.
US-CERT - Reducing Spam