My email inbox is maintained aggressively. It has been for years.
Some people let emails pile up in their inbox. Gmail makes it very easy to do so. Not me. If it's in the inbox, it's a drag on my conscious, and I'm constantly reminded that it is there.
I use my inbox as a staging area for things that require attention. Any email sitting in my inbox is a call-to-action - something I need to do, somebody I must reply to, a task I've sent to myself.
Here are my general rules for the inbox zero:
1. Unsubscribe right away for everything that's not providing immediate value
2. Archive everything that has been read or replied to and doesn't need any more of my attention.
3. Snooze anything that will need my attention at some point in the future
4. Leave important things that must have my attention in the inbox.
When emails start piling up in the inbox, it's almost always because there is something big and hairy at the bottom that requires my attention, and once I have taken care of it, all the rest will magically disappear.