Upod's David Hochman found this tool, which he says sounds neat, but NB neither of us have used it enough to 'officially' endorse it:

From Goodexperience dot com:

If you suffer from e-mail overload, and if you trust my judgement
from having read this newsletter for any length of time, please
try this out. I've created this to help solve your overload.

I've written previously about my online todo list, Gootodo.com, but
now I've made it easier to try out. You can now create a trial
account in a few seconds just by entering your e-mail address and
clicking on the confirmation mail.

Create your account here:
https://www.gootodo.com

Once you've done so, you can get started clearing your e-mail
overload right away, with one click of the Forward button.

The trick is to forward any big todos in your e-mail inbox to your
Gootodo list, depending on what day - today or any future day in the
next year - you want it to show up.

In three steps you'll be nearly clear:

1. Only forward to today's list what you can accomplish today;
forward others as far as you can into the future.

2. Delete any e-mails after you've forwarded them.

3. Complete any small, sub-two-minute todos right away, and delete
those e-mails.

Done: you now have an empty inbox and a manageable todo list to get
through today..

Forwarding is easy. For example, forward an e-mail to
today@gootodo.com and it will show up on today's list. (Then, of
course, delete the e-mail from your inbox.)

Forward an e-mail to tomorrow@gootodo.com and it will *not* show up
on today's list - but will appear tomorrow.

Forward an e-mail to 2d@gootodo.com (or 2days@gootodo.com) and it
will show up in two days. Or forward it to monday@gootodo.com and it
will show up on Monday. You can even e-mail a specific date - like
14nov@gootodo.com or nov14@gootodo.com, to create a todo on
November 14.

I can almost guarantee that if you try this out, using the method
I've described, you will feel less stressed, work more productively,
and have more time for things that really matter - family, friends,
and creative pursuits. If you achieve all those benefits, after the
first month I'll ask for three bucks a month for an ongoing account.