I'm creating a workflow and I want to send an email to the population that didn't open the previous email in the workflow. How would I do this? I see how to send to those that received and/or opened the email but I don't see a filter for those that didn't open it.
You can query trackingLogRcp and broadLogRcp table. Forst query broadLogRcp table to check whether an email was sent to particular recipient and then can filter trackingLogRcp table to see whether they opened/clicked a email.
There are many ways to achieve the requirement of yours , i just shared one example for the same. You may also consider created a pre defined filter so you do not have to build the same logic again and again.