You can pick say people who’ve opened your email in the last week – or people who’ve clicked between January through March 10 – whatever you want. You can refine your search until you’re satisfied.
You can add additional segmentation too. Cross open activity with any other fields in your list i.e. State, Products Purchased, Gender, Job title – whatever you have.
Using list segments should should significantly increase your open rates and have a positive impact on your deliverability. Questions? Email support@reachmail.com.