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.

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.

Hi there.

For some reason, 3 of 4 accounts I use no longer open on the accounts list. I cannot expand them, I cannot "Get Messages" for them, there's no reaction whatsoever, as in no message in status bar (which works fine, as confirmed with that 1/4 account that still works).

I checked for subscribed folders and all of them are. I even was able to add a new folder, which does get added via IMAP. This is, therefore, not a connectivity issue.

I also checked the Developer Console and Activity Tasks, absolutely nothing shows there.

I removed global-messages-db.sqlite, folderTree.sjon, the .msf files. I checked in Troubleshoot mode. Nothing helps.

This looks like some nasty bug and I am happy to help debugging this further, if you point me in the right direction.

Добрый день! В течение последних двух месяцев периодически пропадает возможность отправлять письма с моей учётной записи на gmail.com. Во вложении скан сообщения. Приём писем стабилен.

На учётной записи ya.ru этой проблемы нет

mail.ru and vk.com (a russian messenger app) recently decided to cooperate closely. On Linux desktop trying to use webmail (using firefox), I have to solve a captcha everytime (extremely difficult, since there is a slider to move until you see distinct Russian words.Btw. I know Russian, but I struggle).

On android however, it's easy: There is a mail.ru app in the playstore, working very well.

I don't want to use mail.u on android, since typing on android is cumbersome.

Sent and received. Please notice the asterisks. Where do they come from? John

Message Sent: Fantasia I and II Georg Phillip Telemann 1681-1767 Kleine Passacaglia Michael Kuntz 1915-1992 Fair Phyllis I saw

Message Recieved:

• Fantasia I & II* Georg Philipp Telemann (1681–1767)

         Telemann’s Fantasias capture the brilliance and balance of the
         Baroque era—each movement a miniature world of counterpoint,
         grace, and invention.

• Kleine Passacaglia *Michael Kuntz (1915–1992)

          A modern take on a timeless form, Kuntz’s piece builds lyric beauty
          over a gently repeating bass figure. (See insert for more)

• Fair Phyllis I Saw* John Farmer (1570–1601)

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?

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

Hello Thunderbird Community Help!

After reviewing and implementing all the suggestions on the Mozilla/Thunderbird support pages and on the internet, I still cannot send emails from my office365 mail account from Thunderbird. I was able to send/receive email messages until about 4-5 days ago. From several different accounts on my laptop. And from two different laptops: one using Windows 10 and the other 11. Now, both will receive emails to their inboxes but neither will send a message.

I have the various set-up parameters set as recommended for SMTP using Oauth2, see below and the attached photo:

Outgoing (SMTP): Server: smtp.office365.com Port: 587 Security: STARTTLS Authentication: OAuth2 Username: Your full Office 365 email address

I have deleted the stored password hundreds of times. I have deactivated MFA with Microsoft. I have deleted the e-mail profile in question many times, and have re-created it using automated and/or manual configurations. And I have deleted stored passwords.

I keep getting this message:

"Login to server smtp.office365.com with username [my.email.address] failed." With three button choices: "Retry" "Enter New Password" "Cancel"

No luck with Retry or Enter New Password. They both result in a brief, failed re-attempt to send the email message, and a return to the previous message and choices.

Pressing "Cancel" results in this message: "Sending of the message failed. Unable to authenticate to Outgoing server (SMTP) . Please check the password and verify the 'Authentication method' in 'Account Settings | Outgoing server (SMTP)'."

Additionally I've reset my MS password several times. And MS seemingly is uninterested in having TBird/me login to my office365 account. I just get this response repeated over and over:

"Login to server smtp.office365.com with username [my.email.address] failed." With three button choices: "Retry" "Enter New Password" "Cancel".

I've spent a LOT of time over the past few days and over the weekend looking for a solution, but nothing so far has worked and I'm at my wit's end!!

Any help that you folks far more experienced with TBird can give me to get things working again would be GREATLY appreciated.

Best regards...

Tony

Some months ago I received an email, but the body of the email was a picture (jpg) from my computer. The sender definitely does not have the image. The content from the sender is missing, and my image is in the body of the email and as an attachment.

This has happened a handful of times over the past 6-9 months, with the same image showing up in emails from various unrelated senders.

I just received an email from my partner who sent me an email with a screenshot attached, but instead of receiving what he sent, I've got an email with my image that randomly shows up in my inbox.

A few days ago it happened, but when I restarted my computer, the unwanted image was no longer present, and the actual email content was visible.

Restarting my computer has not resolved this particular instance.

Does anyone know why Thunderbird is in love with this one image of mine and why it keeps showing up in my inbox in emails from other people?

Sending an email slowed right down, so I saved it and tried to open it from the Drafts folder, a local folder. Drafts was agonizingly slow to open a draft. (I tried this several times to send a particular email.) I clicked the Repair Folder button for Drafts. Then I clicked the Repair Folder for my local Sent folder. Bad move. Suddenly Thunderbird started resending all the emails in my Sent folder. Starting in 2020.

I had to disable my internet connection, then change my Sent Folder back to a server folder and disable my SMTP settings for the moment. Ouch!

Thunderbird doesn't seem to work well with local folders any more.

I have an outlook work email account in Thunderbird. Now I need to add another for a charity role. The first/work one is fine, but I can only receive emails on the second/charity account. I've tried different setting for the outgoing server but I don't really know what I'm doing with that - can you help please? Thank you.

I can receive mail fine. Cannot send mail on gmx.co.uk acct, but gmx.net works on oauth2. But oauth2 is missing on gmx.co.uk It's just not on the pulldown. I tried a new thunderbird acct for gmx.co.uk but oauth2 is still missing.

Thunderbird 147.0 (64-bit) OS: Linux; Fedora 43 Settings:

• smtp.gmail.com
• port 465
• SSL/TLS
• OAuth2
• full email address

This situation started happening about a week ago. I created a new user and had no problem sending email from the same default account. I can also connect to smtp.gmail.com using telnet, port 465. Something is presumably corrupted. I have had this account for many, many years, so I have accumulated many filters and other data.

I received an email on 02/25/2026 that was a egift card from a local small business. The egift card was from with Square account. When I went back into my inbox the next day to use the egift card, the email was gone. I looked in all my folders and didn't see it anywhere. How can an email just disappear? When I contacted the small business, they said they can't honor the egift card without the 16 digit # on the egift card. I showed them the receipt for the purchase but it doesn't not show the 16 digit code for the ecard, only shows the purchase of a gift card. So how do I find this email with the egift card?

this was the email address from the purchase invoice. noreply@messaging.squareup.com

I don't recall the actual email address the egift card was from other than I saw it was from a Square account.

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?

I've checked and double check as well has changed the outgoing settings from 465 to 587. Nothing works. Help148.0 Sending of the message failed. An error occurred while sending mail: Outgoing server (SMTP) error. The server responded: resomta-h2p-555627.sys.comcast.net resomta-h2p-555627.sys.comcast.net Excessive failed authentication, ESMTP server temporarily not available.

So I have a couple of accounts that do this and not on others (Same domain and server) When the messages come through they are doubled like they are on a thread, but the same exact message. All settings in Thunderbird and the server email config are the same for all addresses,. I have three out of ten that do this for some odd reason.

I have just moved all my email accounts to Zoho mail, under my private domain.

My Neil@ box delivers mail to Thunderbird on Windows 11 and to the Zoho app on Android. All seems well there so far as I've seen so far.

BUT my Jim@ account delivers to the Zoho app on Android and to Thunderbird on Ubuntu 18.4. A significant number of messages show up on Android but NOT on Thunderbird. T'bird doesn't have them in spam or trash or any other possible place, and our filters haven't changed since we used a non-Zoho mail server. Besides, if T'bird marks a message as spam, wouldn't the mail server do the same? It doesn't.

This is a pretty serious problem for us, as we do all our work on desktops, not cellphones.

What can I do to find the problem and fix it?

Thank you!