I'm considering switching from Thunderbird to Outlook. I'm not willing to continue with Thunderbird if I can't resolve problems when they occur. I worked with Outlook in a corporate environment 20 years ago and never had any trouble. I wish Thunderbird was as trouble-free.

Sorry You are having issues. This should be fixable. Let’s take a look.

Let's start by trying to repair the affected folder(s). If you are not sure which ones might be, you can do them all or start with your most common folders.

Steps:

• Right-click the folder in Thunderbird

• Select Properties

• Click Repair Folder

(Let Thunderbird reindex and re-download messages for that folder)

Hi ThundaMike,

I followed your instructions on 4 separate folders. Unfortunately, it did not fix the problem. I'm wondering if the repair process did anything, because there was no message, no pause, nothing.

I'm not sure if this is significant. When messages are returned to the Inbox, there is a little yellow 'X' to the left of the subject. Later, the X's are gone.

Thanks, Jamie

Who is your mail provider? Please screen shot the list of affected folders.

Wayne, My email provider is Fastmail, an Australian company and Runbox, a Norwegian company. I've had my email address, jamiegarde@pobox, for about 25 years. They (Fastmail) forward my email to Runbox and Gmail. I use Gmail only as backup for when Runbox is down. I began using Thunderbird about 3 years ago and the folders worked fine until about 2 months ago. The folders didn't become corrupted all at once; it's been a gradual process.

I have hundreds of folders (not exaggerating). Only around a dozen reject updates. If I open a problem folder, it appears empty, even though the email counts are greater than zero. I've tried recreating alternative folders, but the new ones don't accept moves from the inbox either.

Things apparently returning might have a number of causes, mostly around the removal from the server folder failing so they reappear in a subsequent sync. You might want to open the error console (Ctrl+Shift+J), clear it using the trash can icon on its toolbar before you try again to capture any specific errors.

Note: The error console is home to loads of useless rubbish so clearing it at least limits the useless unrelated information to a relevant time frame and actions. Some things to consider;

1. You have hundreds of folders I assume they are hierarchical in nature as hundreds in a list would be about as bad as having none. Right click on of these apparently empty folder and select properties and repair. Any change?

2. What is the location path shown in the properties box in 1. (Use your mouse to highlight the location and Ctrl+C to copy it). Windows has an inbuilt limit to the length of a path at 256 characters. The reality is this usually causes issues as you approach the limit, not just when it is exceeded. But it is worth checking you are not going over the limit.

3. The return

Matt, Thanks for the suggestions. My folders are very hierarchical, up to 6 levels. I counted the characters in the location path, and it’s much less than 256. The first 3 that I checked had 142 characters, 130 characters, and then 159 characters. I cleared the Error Console and tried to repair some folders. These are the new messages that appear in the Error Console. I don’t understand what these messages mean; perhaps you understand them. NotFoundError: No such JSProcessActor 'BrowserToolboxDevToolsProcess' (intermediate value).getAttribute is not a function 3 ExtensionParent.sys.mjs:326:38 (intermediate value).getAttribute is not a function ExtensionParent.sys.mjs:326:38 (intermediate value).getAttribute is not a function 4 ExtensionParent.sys.mjs:326:38 (intermediate value).getAttribute is not a function ExtensionParent.sys.mjs:326:38 (intermediate value).getAttribute is not a function 3 ExtensionParent.sys.mjs:326:38 (intermediate value).getAttribute is not a function ExtensionParent.sys.mjs:326:38 ChromeUtils.import is not a function implementation.js:14:39 Error: An unexpected error occurred im-background.js:102:40 (intermediate value).getAttribute is not a function ExtensionParent.sys.mjs:326:38 (intermediate value).getAttribute is not a function 4 ExtensionParent.sys.mjs:326:38 (intermediate value).getAttribute is not a function ExtensionParent.sys.mjs:326:38

Matt, your #3 at https://support.mozilla.org/en-US/questions/1529333#answer-1757477 is incomplete.

I can't image what is causing this. But I haven't yet seen mentioned that you tried Help > Troubleshoot Mode?

I tried HELP and Troubleshoot before contacting Mozilla Support. Nothing was addressing my problems, and no one else had similar issues.

Since no one at Mozilla has a solution that fixes my corrupted folders, I plan to set up Fastmail (the company that bought POBOX) to work with Outlook.

In the meantime, since I can't move some of my emails to folders that are corrupted, I'm moving those emails from my inbox to a new folder called "broken folders".