Thunderbird Community Forum

I've been running Thunderbird 145.0 very smoothly under W11 since 145 was released on esr. 24 hours ago, after making no changes to any software at all, I found that the following message appeared when i tried to download mail routinely from my Gmail server.

It reads 'Unable to write the email to the mailbox. Make sure the email system allows you write privileges, and you have enough file space to copy the mailbox'.

Does anyone else have this currently? I have used Thunderbird for over 15 years without this occurrence.

And yes, I do have write privileges (or I did until 24 hours ago) and there's plenty of space available.

I have a backup profile available but before I turn to that is there anything else I can try?

Thanks.

Hi all - I'm running Thunderbird (14.05) on a desktop Mac running Sequoia 15.7.2

In my Local Folders, I have sub folders which in turn have a large number of subfolders. All of those sub folders are automatically listed alphabetically as they're created. In the last couple days, a fairly random selection of six folders from topline folders, sub folders and subsub folders have been shifted to the end of the alphabetized list and I have absolutely no idea why. I can manually move them back no problem, but I'd really like to stop it happening again! Also, I've tried clicking on the topline folder and choosing to sort by subject, but it changes nothing. Even renaming an mis-listed folder to a new name does not make it move to its correct place in the alphabet. Any ideas? Thanks

Dear Community,

I have installed Thunderbird on a new system and imported my mailbox and archives from my old Mac (both running macOS). I am currently using macOS Monterey 12.7.6 and Thunderbird 40.5.0 ESR (64-bit).

All messages—whether imported or newly received—both in the Inbox and in archives are showing the month as April (i.e., xx/4/xx). This issue also appears in the email body when replying or forwarding messages. Please note that the day and year are correct, only the month appears incorrectly as “4” (April)on all messages.

Messages in the imported local folder archives display the correct dates. I have email folders going back to 2006, and I would greatly appreciate your guidance to resolve this issue.

Many thanks in advance, Leonardo

Since last night my emails in 3 accounts won't send in thunderbird. I get the following message

the message could note be sent because connecting to the outgoing server SMTP mail.optusnet.com.au failed. The server maybe unavailable or is refusing SMTP connections. Please verify that your outgoing server (SMTP) is correct and try again.

The provider Optus has confirmed it doesn't have any issues.

Is there a problem with this with Windows 11 which i have just downloaded 5 days ago?

Does anyone have any suggestions?

Thunderbird was sending and receiving just fine until a couple hours ago. Now, I cannot send anything to anyone - including my email provider. The message is: "Outgoing server (SMTP) error. The server responded: (C18) RBL restriction: Blacklisted by Internal Reputation Service" I verified all the settings (though I changed nothing prior to the problem) and all is correct. I've checked with tech' support and they verified that my address does not have a Blacklist. I've restarted the program and restarted the computer. I've also donated several times to Thunderbird. Before I change clients, I thought I'd see if anyone had a fix for this. Thanks, D

I was trying to change the time emails are kept on the server so I went into "Account Settings" and now Thunderbird is locked onto this page. I get a "Mozilla Thunderbird not responding" message when I try and click on anything and I can't get out of this page nor access my Inbox. I've tried starting Thunderbird in Safe Mode which didn't work. I then uninstalled and reinstalled the latest version of Thunderbird but when it starts it goes straight back to the frozen "Account Settings" page. I've checked my profile and there is a new profile that was created with today's date. There is also a profile from June 2025. If the old profile contains all my emails and folders up to yesterday, that would be OK.

I have been using Thunderbird for months on my new computer. Last night when I brought it up, a new screen said "Unable to Connect" followed by good information like check the network connection, firewall, etc., make sure Thunderbird is permitted to access the web. Plus, the PC bubble communicated "Authentication failure when trying to connect to server imap.comcast.net".

I have checked everything (looked around) and all seems fine. However, I am a "senior" and maybe I missed some communication along the way. I am getting emails on my iPhone and on the Xfinity website, but Thunderbird is not connecting to the server now. Do I need to change any settings?

Hello.

I have added a new account to Thunderbird, and it is not syncing to show new messages. I am getting a pop-up from Tbird saying "The certificate for mail.newcreationloughborough.uk is not valid for that server ..." etc. I have gone through the procedure titled 'Troubleshooting email client warnings about invalid server certificates' to add Norton's certificate to my email app (as directed by the 'resolve' link in the 'Resolve email sync issues caused by certificate warnings' from the Norton EE Cyber Security add-on), and it tells me that the certificate is already installed.

What can I do next to get it to sync?

Hey, after I opened Thunderbird earlier today, all my public keys and my own private keys have simply disappeared. Thunderbird says it can't find my private keys. I didn't change any settings. What can I do?

I've been doing this for (literally) decades.

If I initiate a search in all local folders, for example all messages to, from, cc or bcc a particular e-mail address, the results (as of about a week ago) now ONLY return messages found in Inbox or Trash. Also, after returning those results, the search indictor continues to 'spin' as if it's not done but still searching. None of the messages in my Sent folder appear in the results.

If I change my search to specifically look in the Sent folder, I get all the remaining messages I'm looking for. But it isn't helpful to have to perform two separate searches to get these two separate result sets.

I've tried quite a few things. Any ideas?

J'ai dans mes carnets d'adresses Address Book récupéré par Carddav il est marqué comm carnet par défaut. Lorsque je crée un nouveau message, il n'apparait que très burèvement puis est remplacé par un autre carnet. Comment faire pour qu'il apparaisse tojours por pouvoir slélectionner mes correspondants ? Merci de votre aide.

I am getting the following error message in Thunderbird. Unable to download email to mailbox. Please make sure that the file system has write permissions and that there is enough disk space to copy the mailbox. Write permissions are available and there are 735 GB free.

So I have a self hosted Exchange and I have no problems using it from apps like Google Mail, Outlook and such, plus I can login directly to its .../EWS/Exchange.asmx through a browser. However, when trying with Thunderbird 145/Linux, I always get that username or password are incorrect, but it doesn't tell me exactly what went wrong and how it tried, so I'm in the dark why it is happening. Note: exchange's url is on a different domain than my account.

Basically it's either this message: Authentication error.

Component returned failure code: 0x80004005 (NS_ERROR_FAILURE) [nsIMsgAccountManager.createIncomingServer]

Or similar if I try to get message from inbox.

Also weird things happen during configuration, like attached image (note that I've tried different URL permutations)

TLDR; how do I diagnose the issue, or ever better, how to connect? TIA

The Android Thunderbird app has recently started bunching emails together in the inbox. I'm not talking about displaying a threaded view. What I'm getting is that when I select an email to view, Thunderbird opens up a small group of emails from the same sender. It doesn't seem to have any rhyme or reason to it either... emails displayed might be from the same day or different days. It's extremely irritating! It means that in order to view an email, I have to poke it once, and then again... assuming that the one I want to read is at the top of the displayed list. Why has TB started doing this, and how do I stop it? Thanks in advance, Ian

Dear demons, when will you release a new update that will fix the old update? When will all the normal features be working? It's time to get back to real work for the benefit of society.

Hi! I´ve got to mark a lots of spam and wished to kept them in my spambox. The problem are that i got to have them i my inbox and must remarking them as spam again. Why are the mail obviousely marked as spam still coming in to my cleaned inbox? Thats are very irritable !!!

Best regards Lars

I recently installed Thunderbird for use with Gmail. I have created several message filters, but they keep disappearing. I have found that multiple filter files have been created:

Directory of C:\Users\shrdl\AppData\Roaming\Thunderbird\Profiles\ae352sn6.default-esr\ImapMail\imap.gmail.com 2025-10-28 22:30 385 msgFilterRules.dat

              1 File(s)            385 bytes

Directory of C:\Users\shrdl\AppData\Roaming\Thunderbird\Profiles\ae352sn6.default-esr\Mail\Local Folders 2025-10-28 19:07 241 msgFilterRules.dat

              1 File(s)            241 bytes

Directory of C:\Users\shrdl\AppData\Roaming\Thunderbird\Profiles\ae352sn6.default-esr\Mail\pop.gmail.com 2025-10-26 11:03 0 msgFilterRules.dat

              1 File(s)              0 bytes

Any idea why this is happening? Thanks

I keep getting an alert saying I need to update my email account. How do I do that? (BOTH of my email accounts work fine on my home computer, but neither works on my classroom computer. I'm a teacher).