I'm using Windows 10 and Thunderbird version 78.9.0 I presume you are talking about the 'FROM' drop down list which shows account email addresses. I find they are listed in the order they were created. But the 'Default Account' will be listed at the top even if it was not the first account created, but subsequently set as default. Identities to a specific account will be listed below the main/default account identity and in order created.

If I delete an account and then add again, providing I have not set it up as a default account, then it appears at the bottom of the list with any added alternate identities below it in the order I added them.

I have managed to locate how to change the order of the display in the 'FROM' list. It also changes the order of the accounts in the 'Folder Pane' display.

In Thunderbird

• Help > Troubleshooting Information
• Under 'Application Basics' - about 8th in list is 'Profile Folder' - click on 'Open Folder'

A new window opens showing the contents of the profile name folder.

• Exit Thunderbird now - this is important.

• Locate the 'prefs.js' file and make a copy of file - put on desktop just in case you make an error and you have a backup of original.

Open the 'prefs.js' file using a text editor like Notepad. Scroll down and locate this line:

• user_pref("mail.accountmanager.accounts", "account1,account2,account4,account5,account6,account8");

it will list the account numbers.

Here is an example of what I changed and the effect it had on Folder Pane and list in FROM.

If you change the order to eg:

• user_pref("mail.accountmanager.accounts", "account1,account8, account2,account4,account5,account6");

Then the account order will change. In the example above the account8 was moved from last to second. Note: make sure you get all the commas in correct location.

How do you know what eg:account8 represents ?

• Look for : user_pref("mail.account.account8.identities", "id2,id3");

In my case it says id2 and id3.

What is id2 and id3 ?

• Look for : user_pref("mail.identity.id2.useremail", "Email address here");

This was a mail account with another identity. The other identity was id3.

• Look for : user_pref("mail.identity.id3.useremail", "other identity Email address here");

Now I know that account8 was for a specific email address/mail account - id2 and I know the other identity/email address. So after making changes, by moving the account8 to second in list and saving the 'prefs.js', I started Thunderbird. Now account8 is positioned as second in my Folder Pane and also second in my 'FROM' drop down list. The alternative identity is listed immedately below - so technically third in list.

Hi Toad-Hall,

Thank you for your posts. Unfortunately this was not the issue I was referring to. You refer to the "From" drop-down list once you compose a message. This is not an issue as the sequence can be changed with the configuration editor or in "prefs.js"-files.

I refer to the "(pencil) Write |v" drop-down list which appears in the Mail Toolbar prior to opening the child window to compose a message. The sequence does not correspond neither to order of creation as with the "From" list nor to account number (as per creating sequence) of account ID. I have not found where this sequence is determined and where it can be modified. Thanks.

A drop-down for Write isn't in TB unless you have an add-on like Identity Chooser, but the order of identities can be rearranged by changing the Sort Order in the add-on's Options.