• Email blasting tools can tell you who is opening and clicking through your emails by listing the email addresses' domains. You can use this information to see which of the organizations you've reached out to are most interested in your work, and use this information to reach out to other similar organizations or pursue any related ideas. We don't suggest buying email lists from other organizations, but check out this ANSWR for suggestions: Should we consider buying email lists from other organizations that have members that may be interested in our issues?
  
• Social Media sites such as Facebook or Twitter can also be useful tools for helping you diversify and expand your network. You can use these to see who is talking about the issues important to your organization and to join the discussion in order to engage a broader audience. On Twitter, for example, you can search for popular Hashtags related to your organization on Hashtags.org or Search.Twitter.com, and start tweeting these hashtags so that people who follow conversations around them but may not follow your particular twitter account can find out about you and what your organization is doing. Having a box on your website for Email signups is always a best practice, as is listing your website on your social media pages, that way these new audiences you are engaging can subscribe on their own.

For more information or alternative resources, check out:

• The Role of Email in Your Communications Mix, Idealware (see "Reach New People and Raise Awareness About the Organization")
• Social Media for Events, Social Source Commons