The theory behind segmentation is that if you can identify groups of subscribers within your mailing list based on certain criteria and then tailor messages that will specifically appeal to those subscribers, then they will be more likely to respond favorably to those messages, boosting your engagement and conversion rates.

The biggest challenge to email segmentation is in collecting the data from subscribers that makes it possible to classify them into segments in the first place and then knowing when and how to use this data effectively to maximize subscriber engagement. Here are some examples of requests from subscribers for details that can be used for segmentation as well as examples of email segmentation in action: