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.

I have Mozilla Thunderbird email application with Windows 11. Recently I have problems opening some email texts, but not all. I do receive the mails and heading, but the contents are not displayed. This goes for some mails, and I do not see any connection as to which ones open and which ones don't. I would appreciate your advise. Bo Dahlberg

I have been using our work Mozilla Thunderbird account for two years and in all that time we have been unable to send emails from our usual email address (sales@freunduk.com) to anyone with a Gmail account. We get no bouncebacks and no indication to say that the email has not been received. Everyone else with other types of email account such as Hotmail or Outlook etc get our emails, but for some reason Gmail is blocked. We send invoices, quotes etc from Mozilla and for anyone with a Gmail account, not receiving our email is very inconvenient. We have put customers on stop for non payment and then realised they haven't received our invoice via email because they have a Gmail address. Can anyone shed any light on the matter please? Is there a setting we are missing which needs changing? I have tried to search previous questions on the forum but nothing has been obvious. All help appreciated.

mon compte [edited]@numericable ne peut plus recevoir de message. on me demande le mot de passe de pop.numericable. Sur les paramètres de sécurité j'ai SSL/TLS et authentification "mot de passe normal". je ne sais pas comment faire pour retrouver ma situation fonctionnelle. Merci de votre aide. Envoyer vos réponse sur mon autre adresse mail [edited]@gmail.com ou un sms au 0033[edited]

Hallo,

ich komme seit Sonntag nicht mehr an meine Mails. Kein Abruf möglich obwohl richtges Passwort eingegeben wurde.

[edited]@alice-dsl.net

diese Adresse benutze ich schon seit über 20 Jahren.

Bitte dringen um Hilfe.

Mit freundlichen Grüßen Thomas Höppner

Can not send emails through RoadRunner Mozilla Thunderbird. Can receive. Can send in Spectrum.net, so email account is working properly. Can send and receive with android phone, just not Mozilla. Can not check for latest updates.

I am having a major issue with Thunderbird not saving Outgoing emails in Send Folder with IMAP setting.

Having three mailboxes two are set to IMAP and the third set to POP3. The IMAP outgoing mail creates an alert that mail was sent but copy not placed in your Sent folder due to network of file access errors.

Outgoing mail in POP3 save immediately to the Sent folder.

I am using the latest Thunderbird update:

• Server Type: IMAP Mail Server
• Server Name: IMAP.kinect.co.nz
• Connect Security: SSL/TLS
• Authentication Method: Normal Password

Outgoing Server [SMTP] Settings:

• Description - User name
• Server Name: smtp.kinect.co.nz
• Port: 465
• Connection security: SSL/TLS
• Authentication method: No authentication

Note: Authentication was changed form Normal Password in order to gain some traction on the issue during trouble, cause and correction actions.

Addendum: The PC was fitted to Starlink https://en.wikipedia.org/wiki/Starlink in preparation for use as sole source for internet connection. That was abandoned due to email issues.

This month I downloaded the current version of Tbird on a new computer running windows 11. Tbird receives all my email but can not send mail. I have an old computer running on windows 7 which has Tbird that was loaded at least 5 years ago. It receives and sends email without problems. The two versions of Tbird are using the same SMTP settings: server: mail.twc.com Port: 587. My email account for Tbird is slengyel@triad.rr.com

I also have a gmail account which receives and sends on both computers without problems. My gmail account is steve.lengyel9@gmail.com.

Both computers run through the same internet network.

I am unable to send emails from Thunderbird. Getting the message: An error occurred while sending mail: Outgoing server (SMTP) error. The server responded: Connection from xx.xxx.xx.xxx refused.

When I check my password under "Tools - Security', I only see a password listing for my 'incoming' server [that I do not have a problem with].

My out-going server setup has "Authentication" as normal password. When I try to send an email, Thunderbird does not ask for a password. Is it possible the error message refers to lack of a password? If so, is there anyway to manually add an STMP password to Thunderbird?

I was able to access my Yahoo email with Thunderbird by using the OAuth2 authentication method. However, I am not able to send a email using the yahoo outgoing server. There is no selection for OAuth2 for the outgoing server. I get the message "The message could not be sent because connecting to Outgoing server (SMTP) yahoo failed." What do I need to do to be able to send email via yahoo?

v147.0.1 (64bit) = latest I create a template. Template used by "send a new e-mail from template" works fine and send with text and pictures. All Good.

I use a Filter that sends an auto-reply from a Template. Sent message have wrong coding (Poland chars are replace to some strange characters) and no picture in it, at bottom of e-mail are some codes.

Seams of BUG in Thunderbird, a many years ago was z bugzilla for Mozilla products, now I found only that forum.

Hello - I suddenly cannot send or receive emails in Mozilla - if I go online and do it via the Spark App, it is working, so not my server.

Your advice please?

Why suddenly has Thunderbird stopped logging my messages that I filter manually even though I have logging enabled? It used to work just fine. It no longer logs ANY message filtering. I have not changed any settings. I depend on it especially to confirm that new filters I set are working properly. How can i fix this?

Unable to authenticate to Outgoing server (SMTP) . Please check the password and verify the 'Authentication method' in 'Account Settings | Outgoing server (SMTP)'.

We have thunderbird loaded on two lap tops. We have three emails that we uses on each lap top. Two are working exactly the same. However the third email is removing messages from the inbox - no idea where they are going, there is not an archive folder, they are not going to trash. On the other lap top, they stay in the inbox. They are IMAP not POP. What can we do to fix this?

Thunderbird version number: 148.0.1 Mail provider: Yahoo Client OS: Windows 10

The issue and steps I tried to resolve: On 1 Jan 2026 I switched from Outlook client on my Windows 10 PC to Thunderbird 146.0.1. I did not import any user data from Outlook but started with a clean install of TB for the new year. I use yahoo.com with POP3 as my email provider. Server Settings: Server Name "pop.mail.yahoo.com", port 995, SSL/TLS, OAuth2 Outgoing Server: Server Name "smtp.mail.yahoo.com", port 465, SSL/TLS, OAuth2

it all worked fine and I was very happy with the setup. Then from early to mid-February I was unable to use my computer. When I finally accessed Thunderbird again, it connected to Yahoo and showed that approximately 800 email messages would be downloaded and started downloading them. After downloading about 100 messages, Thunderbird timed out and I haven't been able to get it to work since.

I have read and followed or tried to follow these articles plus others that I may have forgotten about (not listed in any particular order) - OAuth2 Authentication for Yahoo, AOL and ATT | Thunderbird Help - including all the steps in Please check the following before asking for support - POP access settings and instructions for Yahoo Mail | Yahoo Help - Automatic Account Configuration | Thunderbird Help - Manual Account Configuration | Thunderbird Help - Thunderbird and Yahoo | Thunderbird Help - Send and receive messages in Thunderbird | Thunderbird Help - Can no longer get emails | Thunderbird Support Forum | Mozilla Support - Emails suddenly stopped downloading to Thunderbird 140.2.1esr | Thunderbird Support Forum - Get Messages | Thunderbird Support Forum | Mozilla Support - Cannot receive messages | Thunderbird Help - Problem with Thunderbird working with Yahoo Mail acccounts. | Thunderbird Support Forum

I have removed all messages from the Yahoo inbox and tried to find one or more messages that may be affecting the download. I don't know the best way to determine that.

I use Windows Defender for my antivirus. I don't see anything in Defender that blocks or scans email messages which would prevent downloads, although I could be wrong about that. if this might be the issue, please provide some guidance about how to check Defender.

I have uninstalled and re-installed Thunderbird. In the process I downloaded the setup file for Thunderbird Setup 148.0 and installed that version. It later auto-updated to 148.0.1. Before installation, I removed all external connections from my Yahoo account and completely removed Thunderbird from my PC, including the profile and profile.ini. When I reinstall and switch the account to POP3, Thunderbird captures the App password from Yahoo and connects just fine. But it still times out while attempting the first download of a message. The first several times it timed out, an error message was displayed but now it doesn't show anything. Except no messages are downloaded.

At this point, I don't know what else to try. Since I don't have much experience with Thunderbird, I don't know how to troubleshoot the process (logs to look at, etc.). I don't want to go back to Outlook but I need the email client to work and download messages. Any help would be much appreciated.

A big thank you in advance to all who take the time to read this, especially those who feedback.

Firstly, some quick details about my environment:

• Windows 11 Pro (fully patched).
• Proton Mail account – 2 proton address, and 10 addresses across 3 custom domains.
• Thunderbird 146.0.1 (64-bit).
• Proton Mail app 1.11.0 (5.0.324.1).
• Proton Mail Bridge 3.21.2 (br-215). This has been intentionally set to “Split addresses” mode, where (according to Proton) I can “Setup multiple email addresses individually”, and I have also disabled “Show all mail”.
• I have set up a new Thunderbird account for each Proton Mail address.

After only a couple of days of migrating my Outlook messages over to Thunderbird (in Proton Mail), two items of concern became apparent – this query here is the much more important issue; I’ll raise another question here on the community for the other problem.

Now I understand that all of the folders imported or created in Proton Mail have no association with mail addresses. I also expect – but please tell me if I’m wrong – that on the basis of Thunderbird being configured to “Subscribe” to all folders, as well as having the server setting of “Show only subscribed folders” unchecked for each account, then I should see all messages in all folders across all accounts.

I’ve only just started the migration, but even now I’ve imported ~7,000 messages and – based upon the presumption that all accounts should see all folders and their messages – it appears to be a very inconsistent (and worrying!) picture (see attachment).

So far, I’ve:

• Resynced the Proton Mail Bridge. And resynced it again. And again!
• I’ve even run a repair on the Proton Mail Bridge.
• Before any of the two steps above began, I deleted the accounts and data from Thunderbird. When Proton Mail Bridge has then finally resynced, I added the accounts back in again.
• I’ve even gone as far as deleting my Thunderbird profile to effectively start it all again.

And finally, on a second machine (Dell laptop, same config as desktop above), I installed the same three apps and then added only one account to Thunderbird, which returned me just the one single message in the Inbox - absolutely nothing in any of the folders.

The Proton Mail app does show all messages in all of the correct folders, so could this be a Thunderbird issue, a Proton Mail Bridge issue, a combination, or something completely different.

As I said at the beginning, any and all constructive and helpful feedback will be most gratefully received.

the Thunderbird inbox does not display received emails and does not display new emails.My web host provider,Hostgator, has all the old emails and is receiving new ones. so they are in their files. So the problem is with thunderbird. I have consulted your support and forums, tried troubleshoot mode... When I right-clicked on the input file and clicked on repair the display went blank and the emails vanished....also at midnight

on 1/16/26 I no longer receiving new emails.

your help will be appreciated

Lance

A small proportion of my sent emails are not appearing in my sent folder I use a Gmail account via IMAP. I've checked my account settings, and the sent folder is checked correctly.

Hello. My name is Chris Bottle and I live in Australia. In the last couple of days I've discovered that I'm unable to send emails. I've checked my IMAP settings are they are all correct. My email provider is Telstra Australia. When I send an email I get a reply back "An error occured while sending email. Outgoing server SMTP error. The server responded; Connection refused - OB119 .103.224.52.151 is blacklisted in Abusix Mail Intelligence and then two lines of text prefixed by https;/lookup.abusix and further text. I checked with Telstra and after much checking they could find nothing their end. I'm not that computer literate and freely admit that this problem has bamboozled me. I hope somebody can help with this problem. Many thanks. Cheers, Chris