Try right-clicking the iCloud account name, select Settings > Synchronization & Storage > Advanced…, and put a check mark next to any folder you want to be available in Thunderbird.

Does that help?

I’m not sure how to read "INBOX^foldername", but in case you are using a ^ character, that may cause issues. In any case, does that folder synchronize with folders (or is it available) on the server?

Also and in general, uninstalling Thunderbird should retain the profile data and hence any account settings and email used before uninstalling, unless that profile data was deleted using the profile manager. Therefor I wonder why you didn’t see it after reinstalling, and so there may be another profile on your disk. You could check by (temporarily) adding -p to the Thunderbird startup link - see Using multiple profiles for more info. If you ever need to reinstall, backing up that profile folder(s) and the parent profiles.ini file could save some time setting things up.

Tonnes said

Try right-clicking the iCloud account name, select Settings > Synchronization & Storage > Advanced…, and put a check mark next to any folder you want to be available in Thunderbird.

Thanks @Tonnes, that seemed to do the trick.

Tonnes said

I’m not sure how to read "INBOX^foldername", but in case you are using a ^ character, that may cause issues. In any case, does that folder synchronize with folders (or is it available) on the server?

The filename format was automatic- "INBOX^" was default from Thunderbird which was a little strange. I was not able to delete this folder until your solution above.

Tonnes said

Try right-clicking the iCloud account name, select Settings > Synchronization & Storage > Advanced…, and put a check mark next to any folder you want to be available in Thunderbird.

Have you set up Thunderbird to auto expunge? Choose Tools -> Account Settings -> Server Settings for the IMAP mail account and select Clean up ("Expunge") Inbox on Exit. This will compact the Inbox folder when you exit Thunderbird - if not, messages may be marked for deletion, but left untouched. If you check "Empty Trash on Exit", it will also empty and compact the Trash folder when you exit.

If the issue is not about messages remaining in Trash, but Inbox messages that can’t be deleted, try following the steps in the Cannot delete messages article.

If that doesn’t help, please have a look at this article.

Does any of this help?

Tonnes said

If the issue is not about messages remaining in Trash, but Inbox messages that can’t be deleted, try following the steps in the Cannot delete messages article.

Thanks @Tonnes, this was helpful. I deleted the account completely (ImapMail > [email protected]; there were 6 versions from me trying to delete and start again from scratch!), and tried starting anew using these instructions but still no luck.

I continue to get the message "The current operation on 'Inbox' did not succeed." This is well documented in other threads, but I can't seem to find a solution that fits my problem here.

Since you reinstalled Thunderbird after a while and are kind of setting it up as new, have you considered and checked the use of an app password for 2-Step Verification and its allowed apps? Thunderbird may just be seen as an unknown app.

I’m not familiar with Mac/Apple products, so if this doesn’t help, someone else may need to assist.

See Apple support article A similar question

Tonnes said

Since you reinstalled Thunderbird after a while and are kind of setting it up as new, have you considered and checked the use of an app password for 2-Step Verification and its allowed apps? Thunderbird may just be seen as an unknown app. I’m not familiar with Mac/Apple products, so if this doesn’t help, someone else may need to assist. See Apple support article A similar question

I found 2-step authentication a nightmare to have properly set up across all devices and Thunderbird, so I reinstated a normal password. I found that things were working much better using a normal password vs app password.

I see, and can agree... But are you sure it should still work without it? You could also set it up just for testing - if things work, it may be required.

Tonnes said

I see, and can agree... But are you sure it should still work without it? You could also set it up just for testing - if things work, it may be required.

Interestingly, Polymail (another client) requires 2-step authentication for iCloud accounts, so I thought I'd turn things back on to give Thunderbird a second chance.

Alas, after (once again) deleting my account in both Thunderbird and the ImapMail folder, I still have the following errors:

- Cannot delete emails - Emails do not save to the sent folder, or any folder that I direct it to - When I add my iCloud account, it never brings back all folders, until I go to Synchronization & Storage > Advanced > do nothing, and then restart Thunderbird.

I am seriously contemplating using a different client!