Have you checked in account settings that Thunderbird should be checking for new messages on startup? This is a per account setting in server settings.

Go to Connection settings These can be found in setting by searching connection and clicking the "settings" button. The default is no proxy I would also encourage you to enable DNS over HTTPS for your own security if it is not already enabled. That will mean DNS resolution will be undertaken with cloudflare by default

https://www.cloudflare.com/en-au/application-services/products/dns/

It will also mean hat your DNS requests are encrypted and not passed around in plain text but a more complete lay discussion of this is at Wikipedia https://en.wikipedia.org/wiki/DNS_over_HTTPS

Yes, that box is checked, and it seems to check for new messages on startup without any problem. However, it does not check for new incoming mail after startup, which makes the product useless to me.

I have now also completely uninstalled and reinstalled Thunderbird and the problem persists.

I have now also completely uninstalled and reinstalled Thunderbird and the problem persists.

Did you also uninstall your profile (user data)? If not, your profile is still in use so if the problem is with your profile, it will continue. In that case, try a new profile.

I copied my data before uninstalling, installed a new copy, ran the new copy which generated a new profile ID, shut down the new copy, and then moved my data into that new profile folder. Is that what you mean? Abandoning all the saved in/out boxes from my current accounts isn't an option so if there's a third option I'm missing, please advise. Thank you.

I copied my data before uninstalling, installed a new copy, ran the new copy which generated a new profile ID, shut down the new copy, and then moved my data into that new profile folder. Is that what you mean? Abandoning all the saved in/out boxes from my current accounts isn't an option so if there's a third option I'm missing, please advise. Thank you.

First, see if the problem goes away in Troubleshoot mode. If it doesn't, set up a new profile and add one account to it. If the problem goes away then, add the other accounts.

Using Troubleshoot Mode did not fix the issue. I created a new profile and added a seldom-used account to it. The new profile seems to check for new messages normally. How do I migrate my inbox, outbox, archive, etc. from the old profile to the new profile? Is it just a matter of copying everything from the old profile folder into the new one?

Using Troubleshoot Mode did not fix the issue. I created a new profile and added a seldom-used account to it. The new profile seems to check for new messages normally. How do I migrate my inbox, outbox, archive, etc. from the old profile to the new profile? Is it just a matter of copying everything from the old profile folder into the new one?

Yeah, you could try copying everything from the old profile folder into the new one.

I copied everything from the old profile to the new profile. The new profile no longer checks for new messages. Any thoughts on next steps?

I copied everything from the old profile to the new profile. The new profile no longer checks for new messages. Any thoughts on next steps?

As I expected. The only thing to do is make another new profile and add the accounts to it.

Understood. How do I add my outbox, inbox, etc. to the new profile once I've created it? Copying the files manually just seems to have migrated the problem, whatever it is.

I would suggest a new profile, then create the mail accounts but do not download anything. This will create all the correct account data in the new 'prefs.js' file.

• Exit Thunderbird - this is important

Access profile folders. In old profile:

• 'Mail' folder contains 'Local Folders' folder.
• Copy 'Local Folders' folder.

In new profile

• In 'Mail' folder - delete the new 'Local Folders' folder
• Paste the copied 'Local Folders' folder into Mail' folder thus replacing it.

Now to do the mail accounts In old profile:

• 'ImapMail' folder contains imap mail account folders.
• Locate the mail account name folder and copy it. Let's say it's called 'imap.gmail.com'

Note: you can open a 'Inbox' mbox folder (no extension) using a simple text editor program like Notepad++. Then you can check contents to see the email address.

In new profile:

• 'ImapMail' folder contains your various new imap mail account folders.
• Locate same gmail account name and delete it
• Paste in the original gmail account name folder of same name thus replacing it.

Repeat same process for each imap account name folder.

Address Books: Please note you can import them but whilst in profile you might as well just copy paste. In old profile

• 'abook.sqlite' is the Personal Address Book
• 'history.sqlite' is the 'Collected Addresses'
• Copy both of those files

In new profile:

• Delete the 'abook.sqlite' and 'history.sqlite' files, they are new and empty at the moment
• Paste the copied 'abook.sqlite' and 'history.sqlit'e files into profile name folder thus replacing the deleted ones.

If you have more address books eg: abook-1.sqlite, abook-2.sqlite Those can only be imported once you start up Thunderbird, you can use:

• Tools > Import >
• select 'Import a file' and click on 'Continue'
• select 'Import address books' and click on 'Continue'
• select SQlite database file and click on 'Continue'
• A new window opens and you need to locate the 'old' profile to see eg: 'abook-1.sqlite' file
• Select the file and click on 'Open'
• Select the last option 'Create a new directory called 'abook-1' and click on 'Continue'

Do not worry about the name of the address book as this can be manual renamed from within the Thunderbird Address Book later when you have a better idea of what it contains.

• Click on 'Start Import'
• Repeat for all those additional address books.

Thank you for the detailed instructions. The files in the imapmail folder and subfolders are 2kb each. By contrast, my global-messages-db.sqlite file, which you didn't mention, is nearly half a gig. With several accounts that have thousands of messages in their outboxes and hundreds of messages in their inboxes, I'm unclear as to how copying some 2kb files will move the contents of my inbox, outbox, archive folders, etc. to the new profile. If you're confident it will work, you can just tell me "It'll work" and I'll try it. Thanks again.

re :By contrast, my global-messages-db.sqlite file, which you didn't mention, is nearly half a gig.

Did not mention it because it's irrelevant. That is a like a search index of emails, a bunch of header type info used in a search. It does not contain any emails. That would be of significant size in the old profile, but barely anything in the new profile.

re :The files in the imapmail folder and subfolders are 2kb each.

You do not mention whether you are looking at the old or new profile. new profile would not have anything in it - that sounds like you are talking about the new profile. old profile should have a load of stuff.

The 'files' - what files ? If you see eg: 'Inbox.msf' Files with a *.msf extension are just index files and 2kb is so small, it's likely to contain nothing; maybe just enough data for basic contruct. If you only see .msf files then you do not have any emails downloaded. If you see mbox files - they do not have any extension and would be just say 'Inbox', then 2kb is less than an email. That means you do not have full copies downloaded. This sounds more like you have created an account and it contains nothing. Sounds like the new profile not the original old profile.

It would be helpful if you could post a couple of images. It's very important to include all the path directory in the image, so we know what we are looking at. Need images of old original profile showing contents of the ImapMail/imap account name folder

Need images of old original profile showing contents of the ImapMail/imap account name folder

re : Local Folders Did you manage to copy paste the Local Folders folder from old profile into the new profile?

re : IMAP accounts You do not need to worry so much about an imap account. It can only synchronise with server and display whatever is on server. You said it was downloading ok for an account. So what is on the server? Logon to webmail account for email address via a browser and tell us what you see in the server account. If you see tons of emails, then start Thunderbird and let the Imap account synchronise with server to download mail.

if you have any POP accounts - let me know.

Thanks for your continued help. They are all POP accounts. There is little to nothing on the server. Do you still want to see what's in the IMAP folders?