IF it's true that Thunderbird did not have the chance to update your email server, then you just restart Thunderbird normally.

I tried that but when I restarted it everything was marked unread so I quickly closed it before it could fully sync. I'm a bit worried it won't work as you say, is there a --clean start or purge pending actions option for the command line?

I'm not aware of any option that would allow to do that.

Can you logon to your email using browser and write down which one have not been read. Once you have that list, restart Thunderbird and marked those as un-read.

I accidently marked all of the emails in my mailbox as 'read'

This would be the action I would have used:

• 'Menu Bar' toolbar - 'Edit' > 'Undo mark all as read'

If you exit Thunderbird then those 'Undo' options will not be available upon restart.

Synch with server tends to occur almost immediately upon start up unless you do not have connection to internet - eg: router switched off or restarted computer in 'Safe Mode' only or started Thunderbird via 'Profile Manager' where you select to start in offline mode.

Am I missing something, but if you marked all as read then they would not be all unread. Unless everything on server is 'unread' and when you started Thunderbird it showed precisely what was on server - all are unread.

We do not know what was on server, you need to tell us what is seen on the server as accessed via webmail account. If everything is 'unread' on server and Thunderbird upon start up is all unread then both match each other which is expected.

However, if all display as 'read' and you want to reset them all back to 'unread'

• Select folder
• Select an email in list so you have focus on list
• Use keyboard 'Ctrl'+'A' to select all
• When all are highlighted:
• Right click on highlighted emails and select 'Mark' > 'As unread'

SOrry for not including this info. I'm running Mint MATE 22 desktop (~ Ubuntu 24.04 w/o snap) and my Tb version is 128.14.0esr. I'm working with an Outlook server using the OWL plug in.

I tried using the --ProfileManager argument at start up, I got the option to work offline but when the session started it opened a tab for connecting to my Outlook account, none the less. I quickly quit and my emails on the outlook server are not marked all read, but when I restarted Tb locally and killed the Outlook login page the emails were marked all as marked.

I've looked at some of the files in my ~/.thunderbird/<user> folder but have no idea what file does what. If someone can suggest a file or db that I could remove, I'd appreciate.

Otherwise, I'm planning on deleting my current account (or perhaps archive it) create a new outlook account locally. A bit of a PITA, but easier than going through several thousand emails and marking some of them unread manually

It sounds like if server is still as it should be then remove the account, restart Thunderbrd and create the account again and it should display everything as seen on server.

Normally, I would say : You must Exit Thunderbird before doing the following.

~/.thunderbird/<user> folder 'folderCache.json' has a record of all accounts and each folder. It also stores what flag is set eg: 'Inbox', so it can what type of folder and apply appropriate icon, but it also contains info like number of messages and how many unread etc. It can be opened using a simple text editor. So the 'folderCache.json' file would need to be renamed as eg: 'XfolderCache.json' so it does not get used - just in case you need it at some point - this would force a new one to be created when you later restart Thunderbird.

'ImapMail' folder contains imap mail account folders and they contain mbox files of same name as your folders eg: Inbox (no extension) and each would have an index file with a .msf extension eg: Inbox.msf If you deleted the Inbox mbox file and the index file of same name, then upon starting Thunderbird, it should auto recreate the Inbox based on what is on server.

But you have used OWL which I have not - so I'm not sure exactly whether emails still get stored in the same location as IMAP.

Recreating the account would reconnect to server and show everything as on server.

@Toad-Hall Thanks for the additional information. I renamed my ImapMail/Inbox and Inbox.msf files and restarted Tb. That worked!