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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.

hi today thunderbird started showing yahoo popup login and after adding credentials i always get "something went wrong.We could not sign you in. Try again from a different device." Also popup once closed it opens instantly.

i can sign in normally from browser. thunderbird version is 147

is there any fix about this?

thanks for any help

regards

Hi!

I'm losing my mind by the fact that you can't hold to scroll or click to toggle scroll with MMB in Thunderbird, instead it opens a new tab which is completely useless to me since I share inbox and mail reader in one screen.

Is there any way to fix or change this?

If not I'd really like to request this as an option or feature.

Believe my T-bird account has somehow been corrupted. Takes forever to load on PC and always puts new emails in Trash folder. Often does not accept correct password. If I save / backup PROFILE, uninstall T-Bird and delete any Thunderbird folders on PC, if I restore per backup, will I be restoring the corrupted app. Don't want to loose email addresses, thousands of emails and email folder structure. Will a restore work? Thank you. Greg D

PS Version of T-Bird on laptop still puts all new email in Trash, but loads much more quickly, etc.

Since the up date my yahoo and AOL account want me to enter the password. When i do it is not accepted. It is correct since i tried it on a friends computer. I tried to use forgot password and it says I should enable java script and turn off ad blockers. I cannot do this in Firefox nor do I think it will help.

Hi

When Thunderbird is started maximized it overlap taskbar if is set to hide and taskbar won't show until Thunderbird is minimized and maximized. Another way is to press the Win key two times. Then the hided taskbar can be shown/use. The same thing happens to Firefox. Only when is first started. Then if Firefox is minimized and maximized, press Win key two times, press F11 two times then the hided taskbar show/hide normal.

It is a setting that can be changed to start Thunderbird and Firefox in full screen and do not overlap hided taskbar?

It appears how TB handles IMAP connections for outlook email accounts no longer works - OAuth2 connection flow broken, and this is likely due to stricter changes made on Microsoft's backend that is impacting connections going forward.

I have multiple email accounts configured and recently, I have been bombarded by login pop up - likely related to the OAuth2 authentic process.

Whilst I was able to circumvent the authentication process - i.e. not completing the flow process entirely as it expected, newly created outlook accounts appear to reveal two things:

1] There has been a recent change to the authentication process - i.e. the telling sign.

2] There is a now deeper issue when trying to connect outlook email accounts. It seems the reason why circumvention was possible with existing accounts was because they have already passed the OAuth2 process correctly - correct tokens exist. Since this won't be the case for new outlook accounts - no OAuth IMAP access token created, above error is given.

It seems the likely cause is because Thunderbird holds or requests a token that does not contain the correct IMAP audience/scope combination, and Exchange rejects it during SASL XOAUTH2 bind.

For your information, I am using the latest versions and able to configure Apple Mail client - which uses Exchange protocol (not IMAP), without issues.

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?

Normally, I can right click and tell Thunderbird that this is NOT junk, however, when I do this, these emails go back into the inbox and virtually instantly return to junk.

This is from anyone's email address that arrives from one particular website: @legacydigitalagency.com

I haven't come across this issue since I started using Thunderbird 20+ years ago.

I cannot seem to get Thunderbird to successfully connect to my email server on Network Solutions. Neither POP3 or IMAP works. I added an autoconfig of mail.<domain.ext>.netsolmail.net but this did not work. I am using the recommended ports and SSL/TLS settings. I can see from the Thunderbird Tools->Activity Manager that the connection is being refused. I can log into the mail account directly through the Network Solutions web access process. I used to just use a .forward on this account, but now I would like to set it up as my primary email server. Maybe there are other advanced settings on NS that need to be changed. Anyone know if there is something I am missing? I have changed the autodiscover to the autoconfig above in the CNAME and have map, mail, pop and smtp set to values recommended by NS. Do I need to add back the autodiscover setting perhaps? Many thanks for any suggestions.

Good afternoon.

When I receive emails such as password resets, or email verifications, etc., they always contain a line such as "click the link to verify your email", and they never display correctly like they do in other email programs, and I have to literally copy and paste the link in a web browser manually.

Is there a setting somewhere that I am missing?

Hello, I apologize, I am uncertain if this is the appropriate place to post this topic. I am having significant difficulty with the forum system when we require assistance.

I have been using Thunderbird for over a year now, and I have wanted to stop using it since the first month of use. Several times a month, I am unable to send messages even though I haven't made any changes. The message keeps popping up: “The message failed to send. The message could not be sent because the connection to the outgoing server (SMTP) ”server name" failed. The server may be unavailable or refusing SMTP connections. Please check that your outgoing server (SMTP) settings are correct and try again."

This is supposed to be my work email. I understand that ThunderBird is a volunteer platform. And that you do what you can, but I can't afford to be stuck like this for a “yes” or a “no.” You were highly recommended to me by my website host, and I regret it. I am no longer in contact with that person, so I can no longer get the assistance I needed several times a month to get the mailbox up and running again. However, I continue to receive mail at that address.

Is there a way to automatically transfer emails from ThunderBird to Proton Mail? If so, how do I do that, please?

Thank you.

Can not send emails to a newly created outlook.com (free) account. Have tried dozens of different settings, approaches.

My current setup:

 - windows 10
 - thunderbird 140.8.0esr (64-bit),  numerous previous versions also do not work
 - outlook.com (free) account mail provider
 - POP3 enabled (tried IMAP enabling also) on outlook.com account
 - no 2FA or 2FA enabled on outlook.com account, no difference
 - outlook.com web access works fine
 - followed instructions in mozilla support article Microsoft OAuth Authentication and Thunderbird in 2024 
      (https://support.mozilla.org/en-US/kb/microsoft-oauth-authentication-and-thunderbird-202)
 - have done a fresh install on a new machine without an existing profile.
 - have tried various microsoft servers, have tried oauth2, normal password
 - thunderbird account creation works just fine.
 - server settings and SMTP settings match as recommended by support article noted above
    SMTP server settings
        server name: smtp-mail.outlook.com  
        port: 587
        connection: STARTTLS
        authentication: OAUTH2
        user:  xxxxxxxx@outlook.com

symptoms:

 - receiving(downloading) emails works fine.
 - sending emails fails with following messages
     Login to server smtp-mail.outlook.com with username  xxxxxx@outlook.com    failed    followed by 
           Unable to authenticate to Outgoing server (SMTP) . Please check the password and verify the 
             'Authentication method' in 'Account Settings | Outgoing server (SMTP)'

Many people seem to be having this issue with no resolution.

Please help.

In our organization we have moved from an on-premise mail server to M365. We've also added our new EWS-based accounts to Thunderbird. Since there are a large number of users with a significant amount of older mails they want to have access to, they have been asking how they could upload them to EWS now.

From the looks of it, using TB one can either drag and drop messages from the local folders to EWS. Would message copy/move from the local folders be faster if the EWS account was setup over IMAP, instead of over EWS? If so, we could setup another account corresponding to the same EWS identity, but over IMAP, just for the purposes of transferring messages faster.

Thanks in advance for any information provided.

Created new yahoo mail IMAP (PKCE) account using Thunderbird account creation. All seemed to work well. However, new account does not receive mail from "some" other IMAP and POP accounts in testing, including from TB Pro. Strangely, mail sent from oldest POP accounts works. Mail from newer POP gmail and TBPro accounts is not received. TB 149.0b1 Windows 11

This happens each time I open up T-Bird. Somtimes it is Yahoo.mail, sometimes it prompts to log onto aol.mail.com.

How can this be stopped?

________________________

desktop Win11 pro Thunderbird 148.0 (64-bit)

Hi, somehow thunderbird forced me to use OAuth for caldav and carddav. (v140 on linux) Unless I've probably missed something this approach doesn't seem to have considered that people might use more than one device. In the past I had an application password per device with my mail provider. That password covered imap, smtp, caldav and carddav. The application password I could set with a specific name at my mail provider. If the device was lost, compromised or whatever I just deleted that one application password at my mail provider, problem solved.

Now a regular thunderbird setup has the application password for mail and 2 OAuth records per device under "Connected Apps" at my mail provider. But it is not possible to see anymore to which device the OAuth record belong, as there is nothing device specific coming along with these OAuth records, just an IP.

With that perspective OAuth weakened my security options, as I can only guess which OAuth record I have to delete in an emergency case. Did anyone who implemented that with Thunderbird considered that people may have more than 1 device? Maybe even more than 5 devices?

That OAuth approach looks unmanagable to me. Is there a way to switch OAuth off in thunderbird, until it becomes more useable in >1 device setups?

Cheers Tjareson

I have used Thunderbird for many years and and have loved it. However, recently my "Local Folders Inbox" have been extremely slow (deleting emails, reviewing an email, etc.). I have tried every suggestion that I have found without any change: reducing emails in the folder (down to about 75 remaining), compacting and repairing the folder, deleting and rebuilding all of the msf files and global database, disabling all addons, empty trash and junk, clear the cache, disable hardware acceleration, exclusion in antivirus, etc. It has become very frustrating. Any suggestions would be greatly appreciated.

For 2 years have been trying to get Thunderbird to access my mail from The Messaging Co. My old Win 10 laptop has no problem. My new win 11 laptop won't. I have configured the servers over and over but everytime I try to access Thunderbird I get "could not connect to mail server: the connection was refused". Who is refusing the connection? And why? I have re-downloaded Thunderbird several times but the problem persists. I am using Firefox. And using the in and out servers as per my win 10 laptop.

Hello! The other day everything worked as usual, and I shut down the computer for the night. The next morning, Thunderbird immediately crashed/shut down when starting each of the 2 profiles I always use. The 3rd profile, which is the default-release running a different email, still seems to work normally. Thunderbird 115.10.1

I have tried Windows (10) safe mode, as well as thunderbird Troubleshoot mode and working offline, but the issue continued to occur.

I'm at a loss now as to what could cause 2 profiles to suddenly cause it to crash. By the way, one profile is for a gmail account and the other one is for an Outlook account, so they don't seem to be related.

In case it helps, there were 2 Microsoft Visual C++ programs installed or updated, and updates to Microsoft 365 and Google Drive just before the problem started. These were all auto updates in the background.

Any help from the Community would be greatly appreciated. Thank you!