Thunderbird Community Forum

Using MYOB continuously for many years. Tried to send an invoice and the system could not put the Invoice into the outgoing mail server. Message said - Blacklisted referring to my IP address! Whatever that means.

Tbird works on the Android tablet with my domain email account without a problem.

Trying to install on the desk micro PC , WINDOWS 11 64-bit. Using POP3 - Incoming set up is accepted but the SMTP outgoing rejects the Host and defaults to my domain name preceded by a full stop.

Tbird had been working well for 6 months on the PC until Windows crashed and a full install had to be done.

No issues installing & using my GMAIL.COM account, just my long term domain name email.

Any suggestions appreciated. Thks RAB

I have been using Thunderbird with two POP3 Hotmail accounts for some time and I am trying to set up a third account with exactly the same configuration. However, both the automatic and the manual configurations failed. The new account receives mail, but the outgoing smtp server config seems to have a problem. Sending messages times out or keeps prompting for a new password.

The Hotmail account has POP3 and IMAP enabled. Thunderbird is set to receive all cookies. I cleared history and cache after every attempt and also temporarily disabled the firewall.

Any suggestions about what the problem could be?

When I try to send an email, Thunderbird says failed and asks for the outbound.att.net password. I've entered the correct password and the send fails again.

This started happening about a month ago, without me changing my settings, which are to retain all emails unless manually deleted. Probably relatedly, copies of sent emails are not saved in the Sent folder. This is my account on yahoo.co.uk - all the emails are available when I go to yahoo through my browser, so it is just Thunderbird that is not ertaining them. I automatically accept Thuderbird software updates (now 148.0.1)

Hey all, I installed the current version of Tbird on a couple of machines for a friend, one machine worked fine for a month or so, then started giving the "unable to write the email to the mailbox, make sure the file system allows you write privileges, and you have enough disk space to copy the mailbox" error. There is a ton of free space on his C: drive, hundreds of GB. Yesterday I installed Thunderbird to another of his PCs, also no 3rd party AV (both running Win 11), same exact error after downloading a handful of emails from a few weeks ago. To make things weirder he took his laptop (the machine that worked ok for a short time) to his office, where he has a different ISP and it downloaded all of his mail! What is going on here? I have seen plenty of threads about this error, I tried compacting, repairing the folder etc, nothing fixes the problem and Thunderbird sits there not syncing his mail. At the bottom of the window it shows that there are 200 or so emails to download, it looks like they are downloading for a bit, then it quits trying and gives the error. Is there a known cause of this seemingly common error? Are Thunderbird devs aware there's an issue that renders their software unuseable for some users? His mail account is with Brightspeed, an old centurytel.net account. Please share any tips you may have for overcoming this error, thanks!

Thunderbird stopped syncing with my GMX email accounts (I have several) a couple of days ago. It keeps reporting that the attempted connection has timed out. I haven't changed any settings on either Thunderbird nor GMX. Any idea why and how to fix it?

Hi folks. Suddenly I am having a problem with my e-mail account. I was working with T’bird this morning without any problems. Then I went to open my Firefox browser and I got a message that it wanted to upgrade to the latest version, which I did.

Now suddenly T’bird isn’t working. I got the message “ Enter credentials for (me) on smtp.gmail.com”. It has given me a Sign in page. My e-mail address was populated. Clicked on Next and got a message from Google “400. That’s an error. The server cannot process the request because it is malformed. It should not be retried. That’s all we know”

I haven’t made any changes to T’bird. My smtp is still the same. I have just looked at my Gmail on my iPad and the only thing I notice is on the menu list there is a link to ‘upgrade’ - I am not risking that yet!

Any suggestions?

I’ve tried all versions of Thunderbird on my 2020 M1 Mac, and even though I log in correctly, it doesn’t load emails from my account. I used to use Thunderbird normally because I needed it, but I haven’t used it for two months, and now I see that it doesn’t work when I try to connect to my email. It connects to my email normally, but the problem is that when I click on “Inbox,” there's nothing there, and when I click “Fetch Mail” to try loading it again, a message pops up at the bottom saying everything is fine, but in the end, I still don't have those emails. What kind of error is 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.