Yes. There are a number of reasons to segment. Segmenting allows you to:

• Send different messages to different audiences: You target donors, online action takers, volunteers, among other subsets, and match messages to interests.
• Vary frequencies to different audiences: You can send less mail to casual supporters, more mail to “super activists” and active supporters who consistently open and click on your emails.
• Do research: You can investigate which messages resonate with different subset audiences, looking at open rates and click-throughs over time.

There are several different types of information you can use to segment a list.

• Issue or program interest
• Geographic – by zip code, state, country, etc.
• Demographic – including preferences, affiliations, personal data, etc.
• Online activity – from taking online action to contributing content
• Relationship history – including donor, event participant, volunteer, etc

The bottom line is that you need data about your list members in order to segment effectively. Be consistently mindful in collecting and maintaining required traits.