RELATED IDEAS
Trigger rules when an email is read
Problem
Rules cannot use read receipts as a trigger or condition, so automations based on whether a message was opened are not possible.
Request
Add "email was read" as a rule trigger and condition to enable automations based on read receipt status.
This is such a great idea!
So important for automating the cleanup of inboxes. @Front I would think this would be a great rule condition to leverage purging emails (such as notification driven emails) which are taking up space on your network and costing you infrastructure costs while helping us users keep our inboxes nice and tidy so we can get to "inbox zero". :)