Hi Shulamit

I suppose the first thing to say is that in the end you want to end up with a manageable number of emails in your "Next Actions" email category. However, as you are suggesting you need to have a reminder of the priority of these then I can only suggest that you use something like the Start label system in Google or actually create two "Next Action Folders" one with a certain SLA level ie must be dealt with within Xhrs or Days from receipt and another more relaxed one.

It seems to be a unnecessary additional work to start having to create and duplicate tasks in your email.

Hope this helps