This is how my account was shown after I configured Mozilla Thunderbird for Gmail using IMAP protocol.
Mozilla has published Thunderbird and Gmail set-up guide which shows the same [Gmail] folder on screenshots.
Mozilla recommends using Flat Folder Tree add-on to show all the sub-folders of the [Gmail] IMAP’s folder at the same level than your other folders.
However the solution I discovered is much simpler and does not require any add-ons. I am surprised this is not mentioned in the official guide.
Here is what you need to do:
- Right click on the account in the folder pane and select Settings.
In the Account Settings window select Server Settings and click the Advanced button.
In the Advanced Account Settings window change IMAP server directory to [Gmail] and click OK.
- Restart Mozilla Thunderbird.
After restarting Thunderbird all folders are shown in a single-level list.
With this solution you will not be able to see your custom folders (labels) anymore. The workaround is to add [Gmail]/ in front of the label’s name.
After using it for a while I ended up not hiding [Gmail] folder. I found it convenient that folders that I don’t use as often (Sent Mail, All Mail, Spam) can be collapsed, reducing vertical height of the account in the folder pane.