For my part - I don't rely on any aspect of my email system for lists, I find the mixing of tools to be a downhill slope too quickly. That said - if you use Outlook, you could use the flag feature, which allows you to set a specific date flag. That way each day when you check this list you only check the items that are flagged for that day, and once followed up, you reset the flag (or the follow up replaces the original email, with its own flag). I assume many other email programs have similar functionality.
For my part - I clear out my sent items just as frequently as my inbox, filing and deleting where appropriate, and where there is any action stemming from a sent item - either a commitment from me to do something, or a follow up required because I have asked someone to do something for me/give me a response, I add that onto my "Waiting For" list. It gets an original entry date stamp so I know when I put it on there, and then I track the most recent follow up date in the description (eg "Follow up Fred re: feedback on proposal (last on 23/8 )").
Hope that helps...
Do, or do not. There is no try.