Thunderbird Community Forum

I have been using Mozilla Thunderbird for decades and they have even contributed a small amount of money to Thunderbird periodically. Just within the last two or three days all of a sudden I have been unable to send emails with my phone. I receive emails, but I do not send them.

So I opened up a laptop where I did not have Thunderbird and set it up properly through Spectrum using the incoming and outgoing servers as mail.twc.com. and yes, just like on my phone. I continue to receive new emails, but even with the laptop I was unable to send an email.

I received the message"send message error sending a message failed. The message could not be sent because the connection to outgoing server smtp mail.twc.com was lost in the middle of the transaction. Try again."

I contacted Spectrum twice and both times they had me try to send a message through their Web server spectrum.net and that message did go through. Of course then their response is that this has to be a problem with the third-party app meaning Mozilla Thunderbird, and they can’t help with that at all. I sure would appreciate some help because I hate to walk away from Thunderbird as well as change my email address after all of these decades.

Neither my wife nor I can access email on our respective PCs. This has been the case for four weeks. We can access email by our Android phones, but we really want to use our PCs. I've tried to resolve the problem and failed. Previous to this failure, I had an account with BT but this was transferred to EE. When I attempt to log in to my mail account, I receive the message "Could not connect ... :the connection was refused". I can also add is that in my Account settings, Outgoing Mail server I see a message "Connection to server mail.btinternet.com:465 failed."

My old email server was Mediacom (mchsi.com). I had that email account plus a gmail account on Thunderbird. Sometimes people said their emails to my gmail account would bounce. I changed email servers and no longer have the mchsi.com email or Mediacom server and have 2 gmail accounts on Thunderbird. The new one works fine. When I send an email to the old gmail account it bounces back saying "address not found. Your message wasn't delivered to ------@mchsi.com because the address could not be found or is unable to receive mail. 550 5.1.1 I had the tech that sold me the PC look at the settings on Thunderbird for the gmail account and he said they were okay. Where else can he check? Somehow the pc thinks that just that one gmail account is run through or attached to mchsi.com Kathy foggiak@gmail.com

Something horrible and time-consuming has changed within this past week to Thunderbird. My version is 140.7 1esr 64bit. Over the past 4 days or so, I've found I cannot scroll down and see the full emails--until I have to use this new pop-up system.

This is definitely not an improvement in my estimation. Is there any way to undo this?

On Saturday morning 27 June 2026 I tried to login my Orcon email account via Thunderbird (which I have been using for a long time). But my login didn't work, I got a message saying "login to POP3.orcon.net.nz with username habitation failed." On 30th June 2026 I reported the problem to Orcon.

Orcon gave me the following settings for Thunderbird. I have done that and even made a new account: Incoming Server Type: IMAP Mail Server: imap.orcon.net.nz Port: 143 SSL: Off Authentication: On (username and password required)

Outgoing SMTP Server: Mail Server: smtp.orcon.net.nz Port: 25 SSL: Off Authentication: Off

Since then I have spent many hours and going around in circles with Orcon's Technical Support to resolve this, but no luck. They blame Thunderbird. I used Thunderbird Troubleshoot Mode. The message that comes up reads: login to server mail orcon.net.nz with username habitation failed. Please can you check that your server settings above are correct? And if there is a bug? Irma

Cannot send messages. I get an error code:

Sending of the message failed. An error occurred while sending mail: Outgoing server (SMTP) error. The server responded: RBL restriction: Blacklisted by Internal Reputation Service - 73.62.119.4.

This is a recent abberation. I've updated to the latest version of TBird. But cannot understand this message or why I get it. Please help as I forward/send many messages daily.

Thank you

Attempting to install Thunderbird on an additional desktop using same address as my original computer has. That was my question:

Lin answered: Please quote any and all error messages you see, in full, verbatim. Screen shots would be OK.

Who is your email provider?

Have you compared all account settings, not just the email and password?

Here's my answer to those questions: "Authentication error" "probably wrong configuration, username or password."

My email provider is MTA (Matanuska Telephone Association) Yes, I currently use Thunderbird in my other desk top and it works fine.

On my PC Thunderbirds sending/receiving mail says the mail server refused my connection. My laptop works fine. I have duplicated my laptops in/out specifications onto the PC but still nothing works. Spectrum says everything on their end is fine but can't vouch for roadrunner who is the rr in my mail address of ca.rr.com. All this started about 4 days ago. Any ideas on what to try next? Thanks.

Hi, I use thunderbird as both POP and IMAP through gmail. I keep all my emails on my POP thunderbird desktop client. I use IMAP on my thunderbird laptop client, iPhone, iPad via Apple mail when remote, then download the emails to my desktop.

What I want to do is read emails and set them to archive on my IMA laptop, iPhone, iPad. I know Gmail tags the archived emails. How do I stop thunderbird from downloading the archived emails to my POP thunderbird desktop client?

Thanks! Art

Hello,

Everything working just fine last night. Wake up and Thunderbird will not retrieve emails.

Remembered this old message I got so I went through and deleted my second email address, didn't help.

https://support.mozilla.org/en-US/kb/thunderbird-and-yahoo

Checked all settings compared to Yahoo, still won't download messages. I can even send a message with my current settings no problem, and it does login, just won't retrieve emails. Gives me a connection timeout.

Anyone have any ideas?

I set up a filter to move messages to the junk folder. If it's not from a .com, .net, or .org domain, move it. Here's how I set it up... If the "from" incoming message doesn't contain "any of the following" ".com" ".org" or ".net" move it to "junk". It moved .com and .org messages to junk anyway. What did I do wrong? There are too many TLDs to create a filter for all of them.

I have used Apple Mail, GMail and Outlook; i am hoping that Thunderbird will achieve (relative) zero inbox.

My objective is to create an inbox that observes established rules/filters and directs my emails into the appropriate folders. I was hoping that Thunderbird would achieve this objectives but I have so far been unsuccessful.

I would be happy to screenshare with an appropriate technician in order to resolve this issue as its becoming increasingly frustrating.

I have multiple accounts in Thunderbird. I use Unified Folders for inbox. If I click "New Message" while in the Unified Folders view, the message will send from my default account, which is bill@billbauman.com. But, if I want to change my send from account to bill@ntur.ai, where I have a signature configured, the image in the signature fails to load. But, if I change my focus to select the inbox for bill@ntur.ai and click "New Message", the default send from account is now bill@ntur.ai, and the image in the signature loads just fine.

The image is publicly hosted and loads fine in any browser: https://images.int.dreamhosters.ai/account-482257/ceb3563cdab64978.jpg

I tried to make this as simple as possible for debugging, so I change the signature to just the image. Here is the code: <title>Email Signature</title>

I am running Thunderbird 147.0.2 (64-bit) on Windows 11.

I can make a screen recording demonstrating the behavior.

Does anyone have a solution for this?

Thanks all in advance!

I received a spam message this morning that had a "Disposition-Notification-To" (aka Read Receipt) line that had MY email address on it. I honestly don't know why a spammer would do this - but that's not the issue. I have Read Receipts disabled, but Thunderbird generated an email (to me) and sent it to my mail host. This seems like a bug. Even if the Read Receipt has my email address on it (making it mostly harmless), Thunderbird shouldn't have generated the message. Or am I missing something? Thanks.

I have just acquired a replacement PC and installed Thunderbird, and (as happened on previous occasions) I am unable to send emails because the outgoing server settings that were automatically detected are incorrect, and even feeding in those I recorded on the last occasion does not work. I have had a long conversation with somebody at Plusnet Help Desk, who agrees that the outgoing server should be mail.care4free.net and the port number should be 25, and the connection type should be SSL. He also thought that on my "Account settings" screen there should be an option "Account actions" through which I may be able to solve the problem, but this is not there. I think that last time I had this problem, some genius on this forum managed to solve it, and hope that this will again be the case!

Can get(POP3), but can not send emails to a newly created personal outlook.com account.

the following error occurs when trying to send mail: Unable to authenticate to Outgoing server (SMTP) . Please check the password and verify the 'Authentication method' in 'Account Settings | Outgoing server (SMTP)

all my setting are correct per thunderbird and microsoft:

  (smtp-mail.outlook.com, port 587,  STARTTLS, OAUTH2, xxxxx@outlook.com)

thunderbird error log file contains the following: . . . mailnews.smtp: S: 535 5.7.139 Authentication unsuccessful, SmtpClientAuthentication is disabled for the Mailbox. Visit https://aka.ms/smtp_auth_disabled for more information. [CH5P220CA0005.NAMP220.PROD.OUTLOOK.COM 2026-02-28T23:29:21.878Z 08DE7703D4D1982A]

SmtpClient.sys.mjs:452:17 mailnews.smtp: Command failed: 535 Authentication unsuccessful, SmtpClientAuthentication is disabled for the Mailbox. Visit https://aka.ms/smtp_auth_disabled for more information. [CH5P220CA0005.NAMP220.PROD.OUTLOOK.COM 2026-02-28T23:29:21.878Z 08DE7703D4D1982A]; currentAction=_actionAUTH_XOAUTH2 SmtpClient.sys.mjs:578:19 mailnews.smtp: Error during AUTH XOAUTH2, sending empty response . . .

Based on my understanding its seems thunderbird is using SMTP AUTH instead of OAUTH2 as required for newer personal outlook.com accounts. Is my assessment correct? If so, is there a fix?

Hi everyone!

I'm trying to log into my email account on the domain example.com via SMTP. The email account is with yandex.ru. When I try to authenticate, it says the SMTP password is incorrect. I decided to try through Outlook, and it worked. What could be the issue?

Good morning,

I have a Thunderbird desktop client connected to an email on a Smartermail server via IMAP. Receiving mail just fine, but sent mail stalled on the send then gives the following error.

Your message was sent but a copy was not placed in your sent folder (Sent Items) due to network or file access errors. You can retry or save the message locally to Local Folders/Sent Items-chrissy@fruitacoop.com.

I can switch it to save to a local sent folder, but that is not a viable permanent solution. I have searched and followed all suggested troubleshooting steps I could find in the community forums without success.

Steps tried: - completely removed the account and added it back - completely removed Thunderbird and all app data, reinstalled - Tried many suggested "copies and folders" configurations

All unsuccessful. If anyone has had this issue and has any insight into a soluution, I would be forever grateful.