Thunderbird 115 suddenly stopped accepting downloads.

If Inbox is there but empty, try R. click Inbox > Properties > click 'Repair folder' button.

If the Inbox is actually missing, see if it got unsubscribed:

- on the main mail screen in the L. column, R. click the account (just above where the Inbox would be) > Subscribe

The Inbox is empty! There were around 70 messages saved for reference in it. "Try R" means nothing to me. I've opened the properties of the "Inbox" many times, and "repair" does nothing. Since the main mail screen can move the column headings around, the "L" or "R" column also means nothing to me.

The actual name of the "Inbox" --contains only a capital "I". The error message uses "INBOX" - all caps. Don't know the significance of this, but can't change it.

Since the error message insists that "there is no INBOX available", do you suppose that it means on the Proton mail server, or on TB? I have another information request now into Proton Bridge for the same questions. Thanks for your help, Gerald

I've used TB for many years, and keep it up to date.

It is far from up to date. Windows 7 was dropped as a supported operating system with the release of V128 in July of 2024. You are on a last support version for the operating system, but you are not on a supported version of Thunderbird, it is not up to date and it does not get security patches.

I checked with the proton folk and they do not suggest the Bridge is compatible software for windows 7. They support it on Windows 10 and 11.

See https://proton.me/support/operating-systems-supported-bridge

But it suddenly stopped downloads from my email server. Normally everything comes into my Inbox folder and after reading, they are either put into their respective folders or deleted. I had maybe 60 or 70 retained for later attention. (Like due pymnts) I've tried everything I know, even the mail server connection, but somewhere in the process, I lost everything that was saved in the "Inbox" folder. I got to looking for the profile file, and only found 1 that was recently dated. Not sure if a rebuild would be advisable. Nearly all my (50+) folders show up as normal. Just can't find why the Inbox isn't recognized. I tried using TB in both safe mode and troubleshoot mode, to no effect. I DO have win 7 Ultimate and hasn't ever been a problem. The error message I get is: "The mail server for account ***** responded with 'mailbox INBOX does not exist!' The name of the folder is "Inbox" as opposed to the capitalized version, but nothing has changed for years, and never been a problem. Go figure?? After _years_ of use and storage, I'm really hurting without it. Any help or suggestions would sure be appreciated. gshantz

I read this and wondered why it sounded familiar, I had read of a proton mail user with the same problem. Imagine my surprise when I checked and found it was you with a second topic

https://support.mozilla.org/en-US/questions/1592958

Please stick to the original! Perhaps Ed can close this one as a duplicate.

Note that with old software and unsupported software my observation is antivirus products appear to become increasingly aggressive in attempting to mitigate known vulnerabilities. The result is often the antivirus blocks things that were previously allowed. So the antivirus automatically needs to be included in any troubleshooting process.

In this context, I am guessing the INBOX is the IMAP root, not the folder that has your inbox mail. This is fairly common on IMAP servers. The user has an INBOX and all other folders hang off it and various sleigh of hand actions occur to make the folders all look like they are on the same level in the mail client. In Thunderbird there is an advanced button in server settings that drives the name of the server directory that is used. This is normally blank as the correct location comes in via the IMAP commends issues in the connection process.

Now your issue might be antivirus, have you excluded email from any scanning? They tend to insert themselves into the encrypted connection as a fake IMAP server as far the Thunderbird is concerned and fake client as far as the server (bridge) is concerned, so a hard coded imap server directory could be the issue.

You might also ask the Proton folk what is the correct server directory to use with bridge and try inserting that in the relevant dialog in Server Settings > advanced. But really you are on your own as you have a very specialized environment and no one in this forum is going to have windows 7 and a paid proton bridge to even start making tests to see if they can duplicate your issues.

Let's continue here. I locked https://support.mozilla.org/en-US/questions/1592958.