How to change the account order in Thunderbird

Thunderbird doesn't provide a user interface for changing the order of accounts in the left hand pane, but Config Editor can be used to change it.

See the guide here

In my case I have 11 accounts listed including the two special ones, so basically 9 email accounts. I expect to tidy all that up and have only three or four listed by the end of this year. Getting it to put the most important ones at the top has been good.