Outlook flags can be used in many ways, both good and bad. Here’s the bad way: Do you have hundreds of flagged mail sitting in your Inbox from weeks or even months ago? When you see an old flag in your Inbox, do you blur over it because you have so many others there as well? If so, you are definitely using Outlook flags the wrong way. If you leave them there long term, they just clutter up your Inbox and add to Inbox chaos.
The right way is this: commit to keeping an e-mail flagged for no longer than 24 hours! Process all flagged mail within that time, preferably by end of day.
Anything that you think may take longer than 24 hours to process, convert those to true Outlook tasks. You do that by dragging the e-mail to the Tasks icon or banner button in the lower left of the Outlook screen. Then manage them in the Outlook tasks system per MYN principles, as taught in my book In my book Total Workday Control Using Microsoft Outlook.
But back to flags, here is the right way to use them. In my book, I counsel to set flags only on“deferred” replies—that is, mail you intend to reply to today or very soon but just don’t have time to at the moment. Make sure you reply within a day, even if just briefly, and then clear the flag once you reply.
Add to that another acceptable use of flags: use them for any e-mail that includes a task for you, but that you cannot convert immediately to a task. This may be because it will take a bit to decide what priority and date to put on it. In the midst of a fast-moving day, I flag those temporarily as well.
But the key is to not let flagged mail sit for more than a day or so—otherwise they create too much clutter. And in Outlook 2007 (&2010) they clutter up your To-Do Bar task list as well. What I do is take care of them either at the end of the day, as work settles down, or first thing the next morning, before it gets busy. I go through all the flagged mail and either write the reply or do a conversion to a full, dated and prioritized Outlook task. I empty my Inbox completely after that (see lessons in Total Workday Control on how to do all this).
Also, you may know that in OL 2007 you can actually set a dated alert using a flag, but don’t do that. I highly recommend you use reminder alerts only for Calendar items—that is, for appointments. So if a mail item represents an appointment, go ahead and convert it to a Calendar item (you can do that instantly by dragging the mail item to the Calendar banner button in the lower left) and set the alert on that. I detail on page 78 of Total Workday Control (2nd Ed.) why that distinction is so important.