Achiving is within the IMAP account by default. I have no personal experience with apple anything. I refuse to may the extra. However archiving in gmail requires you to leave the mail in the IMAP account. Otherwise archiving does nothing and offers no errors. The server just ignores the command. It would not surprise me at all if Apple did exactly the same thing. Even if you manage to get an archive of gmail somewhere else, gmail still keeps it in the all mail folder, because in their setup that is the archive.

As for the unsubscribe, that sounds like the process of deleting the archived mail is still in progress, (how many thousands of mails are in the queue? That would prevent Thunderbird from accessing other folders when it was to get mail as all available connections would already be in use trying to sync the mass deletion. Showing only the basic inbox and things like deleted is a classic sign of connectivity issues with IMAP accounts.

If you have an apple phone or tablet also connected to that mail, turn them off (overnight perhaps) and that will help the backlog as they have no connection limiting and each will prevent connection from other devices while they do their own sync.

This isn't anything with iCloud, or a paid iCloud account (which I don't have).

Okay, trying this again...

In TB, there's an extension called AutoarchiveReloaded, which is responsible archiving mail in my accounts. It works across any mail account from which it can tell TB to move an email from a mail account to a destination folder within TB (which happens to be hardcoded to Local Folders). Looking at the log it produces in the error console, there are no indications this extension is malfunctioning. All archiving is happening as it should to Local Folders.

Moving along...

The archiving isn't the real issue here. It's an annoyance that I can diagnose later. The REAL issue is when deleting a folder in an IMAP account (which just so happens to be an iCloud account, but could be ANY IMAP account), TB unsubscribes from almost EVERY folder on that account (as stated before).

I need to know what's going on and why this is happening. Again, the real annoyance is having to resubscribe to all of my IMAP folders after deleting a folder from that mail account. Is this a bug? Is it a setting somewhere that is set and I need to get into the console or about:config (if that's available) to fix?

There are no "thousands of emails" in the equation here. And the external archiving has been working just fine for ALL of my accounts up until recently (within the last month or so). All it does is copy the email in question from the target account to a local folder, then deletes the email from the target account to free space. No archiving is to be done, nor is it being done by the extension, in the target mail account. So the comment about the email accounts handling archiving is actually incorrect in this case, and as it's setup before I started using AutoarchiveReloaded, they weren't even archiving to their own archive folders to begin with. I never set that up as it wasn't needed.

There were a ton of assumptions made in that post. That bothers me as an IT professional having done 18+ years on help desk and currently almost 7 in a sys admin role. I know when I know nothing, and know to ask for help. I also know to ask questions to fill in my gaps of knowledge concerning a customer's config before making suggestions. Please feel free to ask questions if you're not sure what I'm doing or how I'm set up. I'll offer up as much info as I can, as I know trying to tech an issue in the dark is frustrating.

All I'm asking for is help figuring this out. And in return I'm willing to spill all of the beans on how I'm doing what I'm doing if that'll help me fix this (or at least change how things are running).