Does it need a reply? Can you reply right now? Reply to it and move it out of your inbox.
Is it something you need to act on later? Make an action in your to-do system. That can be as simple as (in my case) dragging it to Apple Reminders to create a new action with a handy clickable link back to the original email, and setting a meaningful, actionable title like “Review Joe’s proposal”. Now it’s in my actual to-do system, and not a ghost of a vaguely formed request sitting in my inbox and taunting me.
If it’s useful information, archive it, either in the appropriate mail folder or your / your company’s DMS. For my personal use, I adore DEVONthink.
If it’s not something you need to reply to, or act on later, or store for future reference, delete it. I get literally dozens of requests for my time every day, from spammers or trade groups or people who want to sell my company something. I don’t owe those emails my attention.
An email inbox is a terrible task manager. Don’t let it become that for you. When an email comes in, process it one time and then get it out of your sight.