I've found a nice, simple tweak to manage all my e-mail (both work and personal) more effectively (in the sense that it's definitely working for me):
During the last few weeks, instead of looking at my Inbox, I've kept open a "Conversations" smart mailbox (in both Outlook and Mail.app) that displays all e-mail from both my Inbox and Sent Items folders in a single view, but grouped by conversation thread.
(In Mail.app you can just select both your Inbox and the Sent folder, but since I am also active in a couple of low-volume mailing-lists at home, I added those to the smart mailbox as well.)
This greatly simplifies my e-mail workflow, because every "live" discussion thread on that folder is, to all intents and purposes, an open issue that has to be dealt with in some fashion (either by acting upon it or by monitoring).
Expanding the thread allows me to review progress easily, and (most importantly) collapsing it gets the issue out of my way, but not out of sight.
Of course, the irritating penchant that some folk have for changing the Subject: willy-nilly can break this, but fortunately people are mostly lazy and tend not to mess around with it - plus Exchange can still track some conversations if it happens, which is an added nicety.
Acting upon an issue typically means replying in some fashion (which gets tagged on to the bottom of the conversation), and when the issue is closed, I remove the "chatty" non-essential e-mails, add some keywords (in Outlook, of course) and drag the entire thread into my Archive folders.
This makes for a somewhat more crowded inbox, but has a lot going for it:
- I don't have to maintain a To Do list - everything is right there.
- Active issues are continuously bumped up, yet take up very little room when collapsed.
- Flagged items aren't automatically collapsed in Outlook, which makes them doubly useful - i.e., some threads/issues will stand out regardless of activity.
- Random e-mails stick out like sore thumbs (they're the ones not part of threads yet) and can be dealt with immediately.
- Related issues are automatically grouped into conversation forks (not in Mail.app, of course, since its "threading" sucks, but it's plainly visible in Outlook).
- Archiving is both trivial and sensible (i.e., it's a single drag-and-drop action and I can immediately pick what I need to keep).
- Having a single view for your e-mail makes you tidier - there's added pressure to go down into older items, review them, and archive them out of the way.
The reason this works is that e-mail with large attachments (such as the presentations I attended last week, or the feedback template for the latest World Domination Project) tend to be one-offs that you file away (or act upon) quickly, and most of actual, actionable work tends to be a stream of related e-mails within a short span of time.
Outlook's auto-preview is also a massive help in keeping track of updates - thanks to it I now have the message preview pane permanently switched off in Outlook, and still wish that Mail.app had something similar.