If you are wanting to move your entire old profile from old computer to new computer: On old computer: Exit Thunderbird if it is open and running. access : C:\Users\<Windows user name>\AppData\Roaming\Thunderbird\ Copy the 'Thunderbird' folder to a suitable external usb drive or hardrive.

On new computer Exit Thunderbird if it is running access : C:\Users\<Windows user name>\AppData\Roaming folder Paste the copied 'Thunderbird' folder into the 'Roaming' folder overwriting the current 'Thunderbird' folder. All old data is now on new computer.

Start Thunderbird.

Thanks for responding. This is exactly what I did--more than once, uninstalling TB from the new computer in between tries. It never moved any folders but the inbox. A bit of back story in case it's relevant: I previously had to change email servers, and I moved all of my folders from the old server to the new one, so as not to have two sets of the same folders. I then deleted the profile for the older server, as TB continually tried to look for messages from it, and tried to send any outgoing messages to it, even though the new server was now set as default.

If you start up Thunderbird on old computer: do you see all pop mail account folders and emails? do you see all imap mail account folders and emails? Have you chosen to synchronise all imap folders for offline use and then gone into offline mode to get a complete copy of all emails in all subscribed folders into Thunderbird?

I can see all the folders on TB on the old computer, and open all the emails for both accounts.

I have not tried to synchronize anything. I would have to study how to do that and the offline process you mention. Or maybe I could just change the IMAP account to POP. I don't really need it to be IMAP, since I don't access email from other devices. Would that be a good route?

Meanwhile, though, do you have any ideas for the POP account?

On old computer: Exit Thunderbird if running Access: C:\Users\<Windows user name>\AppData\Roaming\Thunderbird Right click on 'Thunderbird' folder and select 'Properties' Make a note of the: 'Size' xxx MB 'Size on disk' xxxMB 'Contains xxxx files and xxx folders.'

Where did you copy them to ? OneDrive or a USB memory stick or external hardrive etc?

Access that copied 'Thunderbird' folder and compare the properties. Is there any difference in size and numbers of folders etc ?

The last copy I made (last night) is almost the same size and has the same number of folders, as the original on the old computer. There's been a little email activity since then, so there's a very small difference in the overall size and number of files. Overall size is 10.4 GB in both. There are 72 folders in both.

I copied them to an external hard drive that I use for backup.

So it would seem the copy to external drive went all ok On new computer: Exit Thunderbird if running Access: C:\Users\<Windows user name>\AppData\Roaming\Thunderbird

What is the difference with Thunderbird properties ?

I had uninstalled TB last night so that further emails didn't get downloaded to the new computer before I got things straightened out. I reinstalled it just now and loaded the copied TB folder onto the new Roaming folder. I checked the size, and it was exactly TWICE as big as it should be. I looked at the email in TB, and all the folders and messages are there now(!) and there are no duplicates of any of the messages. I looked inside the TB folder, and it contains another TB folder (dated yesterday) alongside the two folders with the data I just pasted in today. Is it okay just to delete yesterday's TB folder from inside the new TB folder?

The second account is there now too, but only with the inbox, none of the folders for that account. Again, it was originally migrated to my old Thunderbird as IMAP. If I need to use a different method for getting those folders, can you kindly point me in the right direction? Or should I change it to POP?

Thanks so much!

re :I looked inside the TB folder, and it contains another TB folder (dated yesterday)

Suggest you stop uninstalling/reinstalling Thunderbird as this is not achieving anything. It only keeps removing and adding the program, it does not remove any profile info / 'Thunderbird' folder contained in 'Roaming' folder.

It would seem you pasted a Thunderbird folder inside a Thunderbird folder at some point.

Make sure Thunderbird is not running. Delete the 'Thunderbird' folder which is 'dated yesterday' and located inside the top level 'Thunderbird folder.

re :The second account is there now too, but only with the inbox, none of the folders for that account. As it is an imap mail account, you would need to subscribe to see those folders. So if you want to swap to POP, you have two options: Either : subscribe to see folders, then make sure all settings are setup to synchronise for offline use to download full copies of emails. Then in offline mode, to stop further synchronising, get copies into suitably named folders in 'Local Folders' mail account. Then remove the imap mail account and create a new pop mail account.

OR : Create a Pop mail account for that email address in Thunderbird and then go through the process of moving emails from various server folders into server Inbox accessed via Webmail account and download them from server Inbox into pop mail account Inbox.

How to subscribe to see fodlers in imap mail account: Right click on imap mail account and select 'Subscribe' select folders and click on 'Subscribe' button click on ok

Process for moving server emails into server Inbox in order to download into a Thunderbird Pop mail account. If you have been using an imap mail account for a while, then those emails will be stored on the server. Imap offers a virtual view of the folders on the server, so you can see emails stored in those folders. It works very differently from POP.

If you created a new 'existing mail account' for that email address and this time created it as a POP mail account, then you would only get access to the server Inbox and download those emails. If you had emails in eg: 'Sent' folder, you would need to:

In Thunderbird: Create some fodlders. Move all emails out of the Inbox into those folders for storage. Access webmail account, move all emails from server 'Sent' folder into 'Inbox'

In Thunderbird clickon 'Get Messages' to download them into thunderbird Inbox. Then move all of those 'sent' emails into the Pop 'Sent' folder. Note: You have send at least one email for a pop mail account to auto create a 'Sent' folder.

Repeat this moving and downloading and moving to correct folder to get all emails into the pop account. Once this is done, you can then continue using the pop as usual.

Thanks for all your wise help. I will clean up the profile for the first account and work on the solution to the second account.

This is only one medium-sized part of all that's entailed in setting up a new computer. It's exhausting, at least for a layperson like me. So again, I do appreciate your help.