Rated 4 out of 5 stars

It was very helpful when it worked. Unfortunately, Tbird 68.3.1 update broke it.
The account list is displayed, but the tabs and buttons are all missing. Zero functionality.
Let's hope the dev hasn't abandoned this project. I just converted my numerous accounts to IMAP, making re-sorting necessary. I start to do so and find this addon no longer works.
No joy. =(

Rated 4 out of 5 stars

The "polish" would be maintaining focus/highlight on the selected account. As it is now, when the user moves the account beyond the listbox border and then moves it back into the box, highlighting is lost, making it sometimes difficult to follow movement. Also, when highlight is lost and the user reselects the same account, it doesn't highlight it, but merely borders it with a solid focus outline -- the border would be enough to help follow movement, but unfortunately, this focus outline is lost when the account is moved again.
Maintaining focus/highlight at all times on the selected account would be proper aesthetics.

Also, multiple selection capability for moving groups/blocks would be most welcome.

Lastly, a feature request: smtp list sorting. For those of us with a lot of accounts, it would be great to be able to sort the smtp's to match the account order . Over the years of adding accounts, removing and re-adding, my smtp list is effectively randomized.

This review is for a previous version of the add-on (1.1.1).