No reference folders in Outlook
I particularly hate software that forces me to reproduce my folder system within it (thanks OneNote team, this is the way to go). I have also struggled with Outlook for months until I got a non-orthodox working solution for this problem. I simply do not have any reference or support emails in my main pst file anymore.
Any reference emails are moved to one specific pst file, under each project folder. It only has one Outlook folder (emails), where I have all received and sent mails organized by conversation and time (newest on top). Initially I thought of storing specific project information for each project (contacts, past calendar items, etc), but then discovered it to be a waste of time.
I generally do not delete emails. They are backed up in a gmail account and in my project folders. When a project is done, I move the project folder to an archive folder. With bigger HDs and search software, I don't see any need to delete this information, as long as it is out of your main system. This has saved me a lot of trouble in the past when I needed proofs of communication.
A nice byproduct of this technique is that it also keeps your main pst file very small. Outlook and your backup software will thank you for that.
