Great lessons learned. I have a similar system to your new one. I don't use project management software so my "get to it soon" priority gets tagged as Followup. This means I need to think a bit more or accomplish some other action prior to a response. I try to get to these within 48 hours. My other extra tag is called Review. These are message that I reply to and expect a response back. If all goes well these just pop back up back in my inbox when the response comes back. I can then remove teh tag and archive the message. If that doesn't happen then I look through the Review folder once a week to see if I need to followup.

Of course all of this is a work in progress. Thanks for sharing your system. Email overload is upon us.