Segmentation is probably the most advanced feature within Mailchimp, but it also unlocks so much opportunity for you to really target people by demographic data or engagement data. Here are the top segment options in Mailchimp, IMHO:
Campaign activity
This helpful segment allows you to set up resends to people who didn’t open the last campaign you sent, or purge your list of people who aren’t opening or clicking in your emails.
Contact rating and Email marketing engagement
These two segment options allow you to filter people by how engaged they are with your email campaigns. You can select a star rating out of 5 for the Contact rating, and choose if someone engages with your emails rarely, sometimes or often. Combining the two allows you to archive inactive subscribers or send re-engagement campaigns to them, as well as reward your loyal subscribers and incentivise them to refer new people.
Email marketing status
This fundamental segment option allows you to filter people by whether they are subscribed or not. You can only send marketing emails to people who are actively subscribed to your list, so this is the first step when building a new segment (email marketing status is subscribed). You can also regularly archive unsubscribed and cleaned people, to keep your audience numbers down and save money.
Signup source
This is a useful segment option to allow you to filter people by how they entered your list. If you have connected Mailchimp up to a 3rd party tool or app, you can detect the API and segment people by that source.
Groups and Tags
Depending on whether you have groups and tags set up in your audience, this is a neat way to segment people.
Purchase activity and Customer lifetime value
If you have your store or CMS connected up to Mailchimp, you can track ecommerce generated revenue per campaign. This is essential to helping you understand how well email marketing is performing for you, and gives you a LOAD of revenue data in which to segment, such as customers vs non-customers, customer value, orders placed and lots more, all with dates. Coupled with your engagement data, you can really target people by the three areas most important: demographics (who they are), engagement (are they engaged) and revenue (are they spending).