My goal is always to have an empty inbox. So, emails that require some sort of action from my part but are not urgent I will snooze them (Gmail feature) to a later time. Email that's like "ok thanks for letting me know" and that's the end of that interaction, I will delete. Other stuff that requires more immediate attention I'll let it hang in the inbox for at most a few days and then try to act on them.

I noticed that letting mails linger in sight in my inbox is energy draining or causes me to procrastinate.