Email Marketing Segmentation Techniques

How are email marketers supposed to be segmenting their audience? Is segmentation necessary at all? A recent study by GetResponse looked into what the popular perceptions were among Email marketers and ranked the popular segmentation techniques among these online marketers

1. Interest based preferences
2. Recent Open or click activity
3. Demographics
4. Purchasing history
5. Subscription date

Interestingly 8.5% of the email marketers did not find audience segmentation useful.