As seen via webmail: Gmail stores everything in only one place the 'All Mail' folder. It uses a type a tagging system which it calls 'labels' to faciliate viewing emails in more logical manner generally refered to as folders. Basically, it's a complicated filter system, the labels do not exist as files, they are just a display. So there is one email stored in 'All Mail' and a type of search filter displaying additional visual displays in the 'Inbox' and in 'Important'. Those additional displays are not additional copies.

In Thunderbird : Most people never subscribe to see the 'All Mail' folder as it is a complete duplicate of everything, received , sent and archived.

In Thunderbird, there is no such thing as 'labels'. The folders you see in the Folder Pane are individual storage files and they connect to server - eg: Thunderbird accesses the label called eg: Inbox and all contents are downloaded into the Imap Inbox where they are stored as separate emails from any other folder. There is no comparison to whatever got downloaded into any other folder. So you do have 3 separate copies of that particular email.

1. The original in 'All Mail'
2. The duplicate copy in 'Important'
3. The duplicate copy in 'Inbox'

This means Thunderbird is accurate. If it did not say 3 then something would be wrong.

It means if you delete the copy from 'All Mail' then you will find you lose all copies. It means if you delete the one in Inbox and you get it auto put into the gmail Trash, then all copies get removed. Why ? because when folders synchronise with gmail server - gmail deems you have chosen to delete the email and as there is only one real email stored in the 'All Mail' folder on server, if it is removed then it does not exist, so it cannot display any copy anywhere.

If you just want to delete the email you have in imap Inbox but want to keep the copy you have in imap 'Important', then you need to delete the one in Inbox using a particular method because it must by-pass the imap gmail Trash. In this instance use this method:

• Select email in Inbox
• Hold down 'Shift' key and press the 'Delete' key.

Please note the 'Undo' does not work for this type of deletion. But if required, you can always add another 'Inbox' label via webmail or create another copy from the 'All Mail' folder.

Because email is not put in the gmail Trash, when folders synhronise with server, gmail sees this as a remove the 'Inbox' label instruction. The original is still in 'All Mail' but now it only has one label called 'Important'.

Personally, I do not subscribe to see 'All Mail' nor 'Important'. It just clutters up everything and uses twice as much space etc which is unecessary and I deliberately wanted to get away from using what Gmail thought I wanted.

This means I'm not synchronising everything more than once. New emails are only in 'Inbox' unless I've auto filtered them into suitable folders for storage and organisation. If I want to set an email as important, I apply a Thunderbird tag called 'Important'.

But the bottom line is this, just because gmail webmail only has one folder called 'All Mail' and everything else is just a filtered search based on labels, it does not mean Thunderbird operates the same. Each copy of an email is a separate copy in a separate file.

As seen via webmail: Gmail stores everything in only one place the 'All Mail' folder. ...

I think you're misunderstanding what the issue is. They problem is not that Gmail has an unread message in multiple folders, it's that Thunderbird's overall unread count sometimes counts each of those instances as separate. E.g MyEmail@gmail.com (3) >Inbox (1) >>Gmail (2) >>> All Inbox (1) >>> Important (1)

It's fine that it's listing it in all those places, but the unread count by my email sometimes doesn't reflect the true number. It usually gets it right, but when it doesn't it's infuriating.

I am having the same problem but I use pop.gmail.com rather than IMAP because I store files manually in a variety of folders in Thunderbird (which is why I'm using Thunderbird in the first place.) Every message I receive results in two audible notifications and a double-counting of the number of unread messages. The first one results in a "ding" and a red "1" in my Inbox on the Windows Taskbar. Two minutes later I get another "ding" and the red "1" changes to "2," but there's still only one new message.

I'm running Thunderbird 102.6.1 in Windows 10 Pro.

Any ideas? This has been going on for several months.