Thunderbird Community Forum

This morning I started getting this popup in lower right part of my screen every minute :

Mozilla ESR Thunderbird Connection to server inbound.att.net has been reset

It continues over and over as TB tries to get new messages.

Also, AVG Free antivirus is telling me it has identified a site certification problem. LOCATION: inbound.att.net (POP) Process: thunderbird.exe Detected by: Email Shield

In TB Help it says I'm currently on the esr uipdate channel .....whatever that means Whats the issue here? Can anyone help?

Since the recent update, 157.1, I cannot get the "Get Messages" button to work and it will not download new emails. I can download a previous version and it works just fine. I also cannot stop the auto updating function even though I check the box to not auto install.

A couple of days ago I was suddenly unable to receive email. I can still "Send." This may be relevant. A week or so ago my ATT email started requiring a verification process that required matching up figures. This continued for several days. Eventually I started receiving a "verification confirmed" message w/o having to match the figures and the log-in proceeded as usual. For the last couple of days I have not received the verification message and the log-in as proceeded in the normal manner. I remember a few years ago there was a problem with ATT and Thunderbird having to have a special pass word. It was called a SafeKey. Don't know if this is the same problem.

When I attempt to send email I get the following message: Sending of the message failed. The message was not sent due to exceeding the allowed number of recipients. The server responded: Policy-SC01 You’ve reached your sending limit. Don’t worry, you can send again soon..

My Thunderbird version is 153.2. My email provider is Yahoo.. I use the POP protocol and have set it up so that messages are left on the server for this particular email address because I want to hang on to several important emails. I am not sure if I should be checking "Until I delete them" but it is checked right now. Leave messages on server for X number of days is unchecked. I also have a few other Yahoo mail addresses on Thunderbird also set up using POP but the messages are set up to be deleted on the server so they seem ok so far.

Basically when I delete messages in Thunderbird, it also deletes my messages in my Yahoo webmail inbox and it goes to the trash. When I delete messages directly in my Yahoo webmail, nothing happens. So I then transfer the emails that ended up in trash of my Yahoo webmail to my inbox and they are of course downloaded again to Thunderbird. When I delete these emails in Thunderbird thinking that nothing will happen in my webmail since it is set up to POP and messages left on the server, the messages get deleted again, causing an endless cycle of transferring emails to inbox, downloading them on Thunderbird, deleting the unwanted emails on TB, then seeing all my other emails disappear on my Yahoo webmail inbox.

It started a few days ago. There was a random glitch (not sure if it was on Yahoo's end) that led to the OAuth dialog window popping up every time TB downloads mail from Yahoo. Initially I didn't handle this properly and it led my inbox emails going into my other Yahoo mail accounts. I have finally fixed that glitch and emails appear to be downloading properly to their respective inboxes. But I cannot seem to figure out what is causing my emails to be deleted from the POP server. Should I be unchecking "Until I delete them"?

Greenby Support wants a screenshot of Thunderbird Outgoing Server (SMTP) which I can't find via the App menu or any other means of searching. So I do not know which version we have re your question below and I have chosen one shown at random to allow me to submit my question

TB is sending most of my email to the wrong folder. I had 21 message filters, but then I noticed that a lot of things were going to a folder named "bridge" for no apparent reason. I looked at the filter log, but there was nothing in the log for the last few months.

I did have a filter sending certain messages to the "bridge" folder, but TB is sending things there for no reason. I disabled all 21 message filters, and it is still doing it.

I have version 155.0 and I'm using Windows 11 25H2.

How can this be fixed?

The message filters simply are not working. Not only are they not directing incoming messages to the correct folders, they are also moving some messages in a folder to another folder without a rule!

I did a complete review of my message rules, cleaned them up, had some success, but the next time I opened Thundered to check email, some messages were still directed to the wrong folder. I have used Thunderbird for years, know how to use/create message rules and had no trouble prior to 155.

ALSO - tried reloading Bird 154, but it wouldn't do it because of "Profiles." Bad move there. Frankly, those multiple Profiles are a pain in the butt in Bird and Firefox, a perfect example of if ain't broke, don't fix it.

Firefox 155.0.1 Windows 10

for a week or so now, I get the following message when trying to send" Sending of the message failed. An error occurred while sending mail. The mail server responded: Transaction failed Reject due to policy restrictions. For explanation visit https://postmaster.gmx.net/en/case?c=hi&i=ip&v=149.102.242.95&r=1Mirna-1wPNAF1v2y-00h7M4. Please check the message and try again."

receives fine, will not send

After returning from a 6 day vacation, my wife attempted to download email from her Yahoo email account. There are nearly 200 messages that have piled up but they aren't moving. I've uninstalled and re-installed TB. I've uninstalled and reinstalled the app password in Yahoo. There is no problem with accessing the email via any web browser. I spent 49 minutes on a tech support call with Yahoo and they have said the problem is with TB because they repeated the same steps I have. I checked firewall settings and the only antivirus program on the computer is Malware Bytes and it's not running in the background.

The version of TB is the most recent as of yesterday. I don't see any sketchy looking emails in the web version of Yahoo Mail when it's opened. It's set up as a POP3 account and has been since Cox Internet gave their email over to Yahoo. I'd appreciate any assistance in resolving this because it's currently above my pay grade and tech support at Yahoo.

Thunderbird stopped downloading email in July 2026 on the same day an update was pushed. The problem showed up after an update to TB on 27 July 2026. The weird thing is that we have another account and it has no problem with that TB account downloading. I even moved the profile to another laptop. Yesterday it downloaded 25 of approximately 300 messages and stopped. I had a lengthy tech support call with Yahoo and they concluded the problem was Thunderbird. I've re-installed and updated the program. I've gone through multiple App passwords in an attempt to re-connect. The outgoing mail works. The web based Yahoo mail works. It's not an antivirus or firewall problem. I even archived most of the Yahoo mail from the web and tried to see if I could download messages if there were fewer of them. Even 10 or less would not download.

We have it set up as a POP3 account. The hard drive on the laptop in question has only 10% of its capacity filled. I accidentally removed the other account and had to set it up again yesterday using the exact same steps and it works without issues.
 Does anyone have any suggestions as to what I might try next?

My recollection is that prior to a recent automatic update to Thunderbird 140.12.1esr (64-bit) when I had a message composition window open, there were "SEND" button and possibly a "SEND LATER" button (to the left of the addressee and cc addresses in addition to the keyboard shortcuts (CTRL ENTER and CTRL SHIFT ENTER).

Following the update, there is no longer anything to the left of the addressee information. I have checked the toolbar menus, and there do not appear to be any button options. I can still send messages, but the lack of the buttons is a hindrance.

Seems like soon as a batch of emails download they all open up immediately or at least as soon as I open or delete one they all open. Never had this happening until just late this week.