Please post image of Folder Pane showing 'Local Folders' account so we can see all folders and point out which folder is the one you cannot delete.

Also..you have any Pop mail accounts set up as as deferred accounts - also known as 'Global Inbox' accounts that are using the 'Local Folders' account ?

Please find the image of the folder in the attached. Name of the undelateble folder is Измерительные Технологи... Now it folders turn to bouble with the same name.

I think that I haven't any Pop mail accounts set up as as deferred accounts, but I'm not sure. Could you advice how I can check it?

The image shows the folder you cannot delete, but it does not show if that folder is in the 'Local Folders' account or whether it is in an imap or pop account.

How to tell if you have IMAP or POP or whether POP is set up as a deferred / Global Inbox account. In 'Account Settings' Select 'Server Settings' for account On the right side, at the top, locate 'Server Type' and it will say either 'IMAP Mail Server' or 'POP Mail Server'.

Do you have IMAP or POP ? Please let me know.

IF you have 'IMAP Mail Server' How to get rid of folder:

• In Folder Pane
• Right click on the name of the imap account folder and select 'Subscribe'
• Select name of folder you want to delete and click on 'Unsubscribe'
• Click on 'OK'

Then access webmail account via a browser and delete the Измерительные Технологи folders off server.

IF POP:

• How to check whether it is a normal POP account using it's own folders OR a deferred account set up to use a Global Inbox.

'Server Settings' for account - on the right - click on 'Advanced' button

If you have selected the first option 'Inbox for this account' This is a normal POP account set up to use it's own set of folders in the Folder Pane.

If you have selected 'Inbox for different account' Then you probably selected 'Global Inbox (Local Folders)' This is a deferred account. It uses 'Local Folders' account. In Folder Pane, you will not see the Pop account as a separate account. You will notice the 'Local Folders' account Inbox gets all the Pop account incoming mail.

First of all thank you for your massage

I have IMAP server for my account, but I didn't find the Измерительные Технологии folders in 'Subscribe' subtitle. For me it looks that the Измерительные Технологии folders located in to 'Suppliers Folder' that is subfolder of 'Local Folder' (pls. see the PrtSc in the attached). The 'Local Folder' and Suppliers Folder' haven't option/subtitle 'Subscribe' for that select 'Unsubscribe" and delete Измерительные Технологии folder. By the way all my efforts to change the Измерительные Технологии folder (delete, change name and ect.) lead for the folder just recover back to first view in the same place like the blood in The Canterville Ghost of O. Wilde

Thanks for information and image.

Try this direct method. In Thunderbird

• Help > Troubleshooting Information
• Under 'Application Basics' about half-way is 'Profile Folder' - click on 'Open Folder' button - see image as guide.

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

• Exit Thunderbird now - this is important.

• Double Click on 'Mail' folder to see contents.
• Double Click on 'Local Folders' folder to see contents.

• Double click on the folder called 'Suppliers.sbd'
• Delete 'Измерительные Технологии' mbox file (no extension)
• Delete 'Измерительные Технологии.msf' index file.

Restart Thunderbird.