I usually end up with a list of tasks that I resort and relate to one another, and keep reshuffling as the day goes along. When needed, relevant messages can go in a folder with anything else that's needed to address it so that when I return to it, anything that's needed for it is available immediately.
It just takes discipline and a little OCD! I usually reply and act upon the most important work emails first thing in the morning, and my personal emails first thing after lunch.
I also clear out the spam and notification/newsletter emails while commuting.
Although I don't reach inbox zero every day, I manage to do it every 2-3 days. It gives me great joy!