Rated 3 out of 5 stars

After trying an outdated version, the developer came up quickly with an update. (Thanks!)
The add-on is based on a very good idea, something that is missing in standard e-mail protocol/RFC. On TB39, its widget has a nasty yellow background (still). Would be nice, if user could change its placement (fixed under folder tree) and appearance (at least colour). And the Resubmission button with the logo is almost the biggest one of all in the action bar. It would be better placed in the "More" dropdown menu close to the Delete/Junk/Answer buttons close to the message display.
It is working well though. The question is now, how to gain confidence that it really works. A small (yellow) list of resubmit-items helps to monitor this, in case you do not trust the add-on yet and have some important reminder scheduled.
Possibilities to schedule resubmittal are quite flexible (1 hour, 2 hours, …, 1 days, 2 days, …, user defined). Though the possible actions (flag, remind, flag and flag again) are rather limited, and it would be desirable to have the possibility to move, copy among folders and the like.
Another question is how this will work with TB on different machines. Is a reminder tag added to the message header, and my TB instance at home will react on reminders applied in the office?
Finally, I have to note a little instability when using it for the first time on TB38 (not reproducible). The first reminder went awry, when it popped up the window. I clicked on "Dismiss", reminds again, "Dismiss all", reminds again, "Dismiss", remind, "Dismiss all" really!, remind, … Kill Thunderbird.

This review is for a previous version of the add-on (0.7.9.2).