I used to just put old work email into a folder for each month, where the name of the folder was the date. For work these days, I organize things into folders by project. It' going okay so far, but it's still kind of weird.

I also hate having to find email by searches or threading; I remember things by where they fit chronologically too much. I have some folders in my personal email where I put things from high-traffic categories, but I mostly find things by going, "Oh, I was having crazy dreams just before [larp], so if I want to find [conversation about psychology] I should look at last January, since [larp] was right before I went to Florida, which was on Presidents Day, which is in February." This is why my inbox is at nearly 800 messages now, so I guess I'm saying I have no advice but I have sympathy.

For work these days, I organize things into folders by project.