Thunderbird Community Forum

I have Thunderbird configured to log in to 3 separate email accounts, one of which is a Yahoo email account. Several days ago, a message appeared that notified me that Thunderbird would not connect to the imap account in Yahoo. I tried changing the password by logging in to the Yahoo account via my browser, but Thunderbird still gives the error message. Do I need to delete the Yahoo account from Thunderbird and start over, or is there something else that can fix Thunderbird so I can use it for all 3 email accounts? Thank you.

I'm confident that this is not a Spectrum/Charter issue as I can log into their webmail client and send mail. I can also use the Mail app on my iPhone and send mail from my user@san.rr.com account. My settings are below and have not changed in many months (when SMTP was still working). I've also checked "Saved Logins" and verified that there are entries for IMAP and SMTP and that the password for both is the same and is correct.

Description: IMAP Mail Server Server Name: mail.twc.com Port: 993 User Name: user@san.rr.com Authentication method: Normal password Connection Security: SSL/TLS

Description: TWC SMTP Server Name: mail.twc.com Port: 587 User Name: user@san.rr.com Authentication method: Normal password Connection Security: STARTTLS

This issue started last week on my Windows 11 PC (which has had updates paused since last month). I was previously using TB 128 and have subsequently updated to 140 and repaired my inbox trying to find this issue. When I attempt to send a message, I see "Status" Sending Message..." and a blue progress bar that never changes (TB_sending.png). The dialog box remains frozen for multiple minutes. I had seen a connection error message to SMTP in the past, but it usually disappeared the same day (see other screenshots). It feels like TB is not making a good STARTTLS handshake with mail.twc.com. I've tried switching to SSL/TLS port 465 and that has the same issues.

I downloaded the version on the site but I can't get it to accept my password all I get each time is this at the top of the box

Component returned failure code: 0x804b000a (NS_ERROR_MALFORMED_URI) [nsIIOService.newURI]

Just how am I supposed to understand what that means. I would be grateful for any help you can give I've been using Thunderbird for over 25 years without any problems, I had to reinstall Windows and now I've got this problem.

Recently I posted about this problem here: https://support.mozilla.org/en-US/questions/1580858 In sum, I was having problems both in downloading messages from the Spectrum server and also with sending messages. I've attached screenshots of the error messages.

Matt and David kindly posted some helpful responses. The problem then seemed to spontaneously solve itself and I breathed a sigh of relief. Then a few days later it re-appeared.

This time it's not quite as bad in that I'll get the error messages but then usually a few minutes later I can download the messages or send an email. But it's still a real problem.

I called Spectrum again and this time the rep was adamant that if I can still use the Spectrum webmail feature (and I can), then it's not a Spectrum issue.

Last time Matt asked about my antivirus. I use Windows Defender (and occasionally do a manual scan with Malwarebytes free version), so if I understood him right, I should be OK as far as antivirus interference.

Matt also suggested I set TB so that I download messages at startup and every 15 minutes. I was set to every 10 minutes so I changed it to 15.

Matt said for me to check the Activity Manager. I've attached a screenshot of what that showed a few minutes ago. But I should note that this was after an error message displayed but my email downloaded anyway.

Finally, Matt said I should check the Error Console (Control + Shift +J). I've attached a screenshot of that. He also said I should use the trash can to clear it, so I did. He then said to press Shift + F5 to attempt to get my messages. But on my laptop, F5 just dims the display so no dice on that. But I have a second laptop and F5 is "neutral" on that one so I tried it there. I didn't get any new error message.

However, one of the screwy things is that sometimes I get all my messages as normal, but only after the "Can't connect to the server" message displays. And that's what happened with my second laptop above.

I hope I've provided better info. this time. And I hope you gents can help me with this mess.

Thanks,

Andrew

Thunderbird suddenly stopped working properly today, 15 September 2026. Webmail for the same email account is working normally: I can both send and receive messages. However, Thunderbird is having problems with both incoming and outgoing mail. • Thunderbird connects to the IMAP server, sometimes very slowly, but then does not retrieve new messages. • Sending a message from Thunderbird fails because it cannot connect to the outgoing SMTP server. • Thunderbird's own update also fails. This has never happened to me before. • I have restarted Thunderbird and also restarted the Mac, but the problem remains. • I have not changed any Thunderbird account settings. The fact that webmail is working normally makes me wonder whether this is a Thunderbird problem rather than a problem with the email service. Has there been a known Thunderbird problem affecting connections to mail servers or the Thunderbird updater, and could these problems be related

Almost anything I try to do with Thunderbird, even replying to emails requesting advice, I come up with errors, such as:

Sorry, you have been blocked

You are unable to access thunderbird.net

upstream request timeout

upstream connect error or disconnect/reset before headers. reset reason: connection termination

The 'new' Thunderbird doesn't allow a password entry in server setup and will not prompt me for one. It pops up a Windows toaster message saying it can't connect - obviously. I set the advanced options to not remember the signon but still no success.

Hi I tried to google this but as you can guess that was a exercise in futility.

So I installed thunderbird via flatpac as suggested by the main website

I went to account add a account entered my email and password.

Clicked continue twice setup filled in the info and got a error saying

Authentication error.

Unable to log in at server. Probably wrong configuration, username or password.

now i know both are correct as i logged in vai firefox and checked both excepted.

pic below best i can do dam thing wont let me set window size so it got cropped hopefully gives info needed

so I tried to google the settings of incoming and outgoing 4 out of 5 pages i found where set as the pc has set it.

at a loss now guys no clue what to do any help would be appreciated.

ty in advance.

This only recently started happening. This has been tested on 3 different computers. Windows 10 Pro on all three.

With VPN on: Bluemail works fine.

Thunderbird can connect and download messages, but when I try to send a message, it gives an error.

With VPN off:

Bluemail and Thunderbird both work fine.

The issue has been "An error occurred connecting to mail.mediacombb.net:993." on the server page, where you can "test connection to server" in Account > Server Settings > Security Settings. I get the same error message for each four different accounts. I have no problems with the other two different accounts not associated with Mediacom (MC). I contacted MC and they said my settings were correct and to contact TB. I have read several posts with no real solutions except that was resolved through an update. I plan to switch to a different Linux distro later. I am currently using Big Linux Manjaro with the latest update. Note that I had no problems with TB until last month. I do not do the uninstall/reinstall apps unless it will resolve my issues as a last resort. Second, sometimes I receive MC e-mails and did not run the "test connection to server," then until today while troubleshooting for several hours. I was trying to send out an e-mail, which I had no problems last week. I already went to Account > Server Settings > Advanced and changed the "Maximum number of server connections to cache" from 5 down to 1 with no luck.

  The e-mail server settings are:

imap.mediacombb.net 993 SSL/TLS Normal Password and smtp.mediacombb.net 587 STARTTLS Normal Password They have not been changed since I switched from windows 10 to Zorin 18 to currently Big Linux Manjaro. I attempted to locate a method to check if the server settings were correct via Terminal. M$ Outlook has a test page that you can send to yourself or another e-mail account. Last, MC tech informed me that M$ Outlook is more friendly than TB. I know that I have used M$ Outlook for years and rarely had any connection issues unlike TB. Unlike Evolution, which was my first after M$ Outlook, TB is much better and easier than Evolution. Thank you in advance for your time and advice.

Sometime ago, Thunderbird stopped being able to connect with my GMail and Hotmail email accounts. I guess this had something to do with the change to OAuth authentication. I then switched over to Yahoo accounts which worked perfectly until last night when I installed the latest update, i.e. 153.0.1esr (Meadow). Now, I cannot connect with ANY account whatsoever. Thunderbird just stopped working in my two Windows 10 laptops and it does not seem to work on the Windows 11, either, although I have only tried Gmail accounts on that one (without the update), as I cannot possibly be left without an email handler.

If I try to download my emails, I get a screen that tells me that I should “Turn-off ad blockers“ and “Enable JavaScript“ in my browser, but I have tried several (4) browsers as default with the same result. I don’t have either ad blockers or cookie restrictions in any one of them and JavaScript is enabled in all (it is now by default).

I have downloaded and installed “eM Client” and it works *perfectly*. However, I would loathe to have to abandon Thunderbird and get used to an entirely new program, but which is what I will have to do if this thing is not resolved ASAP.

As mentioned, I think there has to do with the OAuth authentication system.

I have even tried ChatGPT, without success!

And there is no way to revert to the previous version !!!!!

Please do something NOW, or it is, regrettably, goodbye Thunderbird!

Was working OK. Now, "No Apps Available" appears when I try to connect to the Yahoo mail server. The "Find more in Software" button causes the "Failed to start software" message to appear. The reinstall is from the App Center.

It also opens the following link on the Firefox browser which displays a blank page. https://api.login.yahoo.com/oauth2/request_auth?response_type=code&client_id=dj0yJmk9WVZUaWRNUUZSQTBNJmQ9WVdrOVNqbHJUMGhtTkU4bWNHbzlNQT09JnM9Y29uc3VtZXJzZWNyZXQmc3Y9MCZ4PTgz&scope=mail-w+ycal-w+sdct-w&state=AUCYywsENF9wWMx1nhJAefu3yJtqIlLxOCP9laluGgA&code_challenge_method=S256&code_challenge=BhhyhkNZvKm5SUrRFTxgmp3HR7vX26vggsjMoThl4wk&login_hint=randylh%40cox.net&redirect_uri=net.thunderbird%3A%2F%2Foauth%2Fyahoo

Everything has been fine for several years but this morning I now get error: TB could not connect to server mail.twc.com, the connection was refused. Spectrum says everything is good on their end. What do I have to do to "fix" Thunderbird? I can't send or receive any emails from 5 accounts with Spectrum and the emails are there when I log in at WebmailSpectrum.net..

I still use Thunderbird on an old desktop and for the past month or more, I've discovered with some sort of communication error or the direct pop-up that I cannot login to server and it asked me to 'retry'/'Enter New Password"/"Cancel" and it's beyond frustrating. I'm on the verge of just uninstalling this for my emails and use another platform. Before so, since I've been using TBird for a long time, I figured I'd consult some experts here to guide me how to navigate this annoyance. ANY suggestions would be appreciated. Thank you.

Please see attached image of the problem.

I have tried looking on Google for ideas but have not found anything on this or how to fix. Hope someone can please help would be amazing!

Google -

400. That's an error

The server cannot process the request because it is malformed. It should be retied. That's all we know.

Has anyone had issues with Thunderbird sending and receiving email? I can only send or receive when my wifi is turned off on my phone.

I've tried deleting the app and resetting all network settings on my Android phone but still no joy.

Hello, from time to time my Thunderbird on my desktop PC running windows 10 doesn't receive emails, while they arrived on my I Phone 8. Checked my Telstra web mail, all emails are there so what is stopping getting to my desktop PC? I thought the Thunderbird receives emails than synchronize with my I Phone? As you can see from my 2 images the Telstra is up to today as is my I phone But Thunderbird is 3 days beyond. Tomorrow it may back to normal or the next day? I am returning to this message the next day 16/06/2026 1 more message on my I Phone, still nothing on my Thunderbird.

An other problem I get with Thunderbird is that a message appears on the right bottom of my screen: "Mozilla Thunderbird Connection to server mail.bigpond.com timed out" and/or "failed to connect to mail server imap.telstra.com" If I try to send an email after the above notifications, I get the "Connection Refused". I know than to just walk away. I am using Starlink as Telstra here doesn't work as I am on the fringes of Melbourne in a BLACK HOLE. Any help will be gratefully received. Thank you for reading this. Regards Ilio Pieroni