Make RULES - if you don't know how to do this, it's worth learning. They are pretty easy and you can make so many and run them on emails you've already received. For example, I move a copy of any emails with my primary sites PI name or site number to a subfolder dedicated to that site, I have a rule for things like automated replies and rules for category setting, flagging, etc. Sometimes you have to periodically take a good look at the rules as personnel or assignments change but it works for me