Thunderbird Community Forum

Dear community members, Since receiving the Thurderbird release 140.4.0esr on Oct 14th, I have not been able to send email from any of my accounts (2xIMAP and 3xoffice365 through OWL). Nothing has changed in the account settings. Receive works ok. The usual easy fixes do not seem to work (restart, firewall switch-off, etc.). Any ideas beyond having to rewind to an earlier version and rebuild the whole thing (hopefully not!)?

Version 140.4.0esr Build ID 20251010020716 User Agent Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:140.0) Gecko/20100101 Thunderbird/140.4.0 OS Darwin 24.6.0 Darwin Kernel Version 24.6.0: Mon Jul 14 11:30:30 PDT 2025; root:xnu-11417.140.69~1/RELEASE_ARM64_T6020

Thank you for your help! Heli

I've been using Thunderbird to access my Comcast email for two years now, without problems. Except yesterday & today, when I've been unable to send or receive emails, for no apparent reason. Yet, when I connect to my Comcast/Xfinity email via the Comcast browser website, sending and receiving of email works fine. This access problem began yesterday, 10/14/2025.

Same email address I've been using for about 20 years now, and same password. I made no changes to my Thunderbird or Comcast settings. Sending a test email to myself via the Comcast email website works fine. Clicking on the "Get Messages" icon in Thunderbird results in no action whatsoever. Sending a test message to myself in Thunderbird results in about a 40 second delay (usually it's 10 seconds), and then the error message "Login to server smtp.comcast.net with username don-peters@comcast.net failed." It then asks if I want to try again, but if I agree, the same error results. But there is also the option of "Enter new password". Click on that and the same error results, without even asking for a new password. But my password is OK, as evidenced by my Thunderbird settings and being able to log into Comcast browser email.

Yes, I've spent hours on the phone with Comcast on this issue, but they were of no help. One agent claimed that the issue was with Thunderbird, not Comcast, as its webmail worked fine. Two years ago, I had a similar problem I spent hours trying to solve. It turned out the problem then was due to Microsoft Outlook on my PC regularly trying to log into Comcast to ALSO download my email - BUT using the wrong password. Comcast interpreted these multiple failed login attempts as scammer attempts, and blocked ALL email logins from my PC. I fixed the problem by shutting down Outlook. But when I just spoke to Comcast they said the current problem was NOT due to my account getting blocked by them. But they couldn't give a reason for the blockage.

So, I now believe the problem lies with BOTH Thunderbird and Comcast. First of all, Comcast is somehow blocking my Thunderbird access attempts. But Thunderbird is also at fault for not reporting a SPECIFIC email login problem, so that we can address it - and fix it. If Thunderbird can be more specific as to why login attempts are failing, I can get back to them with the evidence - and hopefully solve the problem.

I've been using Thunderbird for about 30 years now, and I hate to give it up. But if this continues, I'll be forced to abandon Thunderbird.

HI and thanks for any help.. I am Popping my gmail and several other non-google accounts. It has worked for years but now I can't pop any gmail after 10/10/25. The mail is there when I go to the gmail web page. It is trying to Pop it cause I can see the message on Thunderbird "there are no messages to download" from that account. I checked and there are no filters. I did a test email. It shows up in gmail but won't pop to my PC. all the other non-gmail accounts are working fine with new messages coming in. I checked all the subfolders and nothing there since 10/10. Any ideas? Thanks. Kevin Brand

Hi, I recently set up TB with one imap account. All fine. I set up a Local Folder as well - mainly to store bulk of old mails.

Then after couple of days, when I sent a message, the system warned me: "your message was sent, but a copy could not be placed in "Sent" folder" due to network or file access issues. Place a copy in local folder instead?"

I recognized, that also, while my account/server seems to connect, no emails at all are fetched from the server actually.

I think there's a strange problem TB internally with ... file access? How to repair?

UPDATE : I checked my TB profile folder, and found the "ImapMail" folder's properties (Win10) showed "read-only". So I closed TB, removed the "read-only" from folder and contents, and restarted TB. But issue persisted. I went back to "ImapMail" folder in my profile - and found it marked "read-only" again. So seems TB itself set it to "read-only", it seems.

Thank you for your advice. Chris

PS:

• Restart : nothing changed
• run in safe mode: nothing chnaged
• repaired folders: nothing chnaged

in the last couple of days thunderbird has stopped showing emails from one particular account. Inbox is only showing messages up to yesterday, and all mail is only showing to the day before (?). The messages are on the proton webmail inbox ok, and are received by the proton mail app on my phone. I have not changed any settings, and it worked perfectly before now

Yesterday and today when starting Thunderbird, message at bottom of page: connected to server(inbound.att.net) Never changes to "checking for new messages" or "downloading messages" so I am unable to get mail. Close and restart does not help. Seems to be be stuck.

On a different computer with the same accounts, functions normally.

Hello,

I’m having an issue with Mozilla Thunderbird when using my WP.pl (IMAP) email account. Thunderbird keeps downloading messages endlessly — it repeatedly fetches headers and then tries to download all emails for offline use, but the process never finishes.

I would like to keep all my messages available offline, but it seems Thunderbird is constantly synchronizing and never stops downloading.

I haven’t tried any troubleshooting steps yet. Could you please advise how to properly set up Thunderbird so that it downloads all messages once and then keeps them stored offline without repeating the same process continuously?

Facendo segui alla seganlazione precedente relativa all' impossibilità di inviare posta con cui avete risposto con mail del 14/10 ore 9.00: l tuo IP è in una blocklist, probabilmente per spam o per altre attività anomale (non significa necessariamente che tu ne sia l'autore).

Prova a farti assegnare un IP diverso dal tuo internet provider (spesso basta spegnere il modem per qualche minuto e poi riaccenderlo).

Oppure contatta IOL/Libero/Virgilio e segnala la situazione.

In ogni caso non riguarda Thunderbird che si limita a mostrarti il messaggio di errore che riceve dal server.

Come mai da un altro pc riesco ad inviarla? Libero non c'entra e le configurazioni di thunderbird sui 2 pc sono le stesse. il fatto che il mio IP sia in una blocklist non mi è stato mai comunicato ne da voi ne tantomeno da Libero, quindi come si spiega il tutto se non per un'anomalia di Thunderbird. Attendo Ragguagli in merito. Cordiali saluti

When I'm composing an email, I can't move the cursor down past bolded text using the down arrow key. It just stays at the beginning of the bolded line. I can scroll up past it using the up key. This started a couple months ago, for some reason.

Thunderbird on a windows laptop is currently only receiving about 10% of my emails compared with my phone and tablet devices which are running Gmail apps. What is causing this? My Thunderbird has been recently updated.

This is the second time I've posted about this. I've tried everything and the problem is getting worse. Thunderbird is deleting messages from my inbox when I retrieve messages from the server. All my settings indicate this should not be happening, but it is. I use the IMAP interface and the latest version of Thunderbird.

This morning after I downloaded messages Thunderbird showed no messages in any of my folders, not even archived! What the heck is going on and how can I solve this? I will have to stop using Thunderbird unless I get this resolved -- and fast.

Kindly assist as i have been having challenges accessing my folders e.g Inbox and sent item box from my thunderbird. Additionally, the icons for add a new account have since disappeared

Hi!

I can't get messages from my Thunderbird account. When I click "Get messages" nothing happens and it usually says "Done" on the bottom left corner. I have to use my domain's webmail account to get my e-mail and it only allows me to read it and delete junk.

I really would love to have my Thunderbird account working again as soon as possible.

Thanks so much, Nancy Pedersen