Thunderbird Community Forum

My TB installation got corrupted due to a hardware/disk issue. On restoring it from backup TB keeps trying to download all messages again. I know this is something to do with the popstate.dat file but I can't seem to stop it. What do I need to do?

Also, I had never noticed this before (because I never looked at the TB file system) but TB created multiple folders for the email account.pop.mail.yahoo-1.com up to pop.mail.yaho-4.com. Why does it do this and is there a way to get back to just one file? Is this something to do with TB crashing or what?

Is it using all of these files or just the latest and how do I know? All of these folders have a popstat.dat file and one has multiple following the popstat-1.dat etc.

I've no idea how to recover from this. Any help would be much appreciated.

hello, i set up my microsoft 365 / outlook account in thunderbid using oauth2 and smtp (port 587, starttls). however outgoing emails fail to send. how can i resolve this smtp issue

Yes, this outlook account was made earlier this year. I've tried all of the "fixes" offered on here and across the internet. I'm changed to to password and got the app password. I've deleted 2FA to see if that would work. I've deleted the Oauth key and it refreshed to a new one. I've done it all and TB-sync is not available to me cus apparently now i'm right outside the app version limit.... how convenient. It's very frustrating as i really like the app and still use it to read my emails but it's very annoying to have to open the outlook app and go through all that just to send an email. I keep getting told it is possible, i've been battling this on and off for months. I cant just get a new email either as i already swapped everything to the outlook one and my work using out look as well. i am able to sync my calendar even but apparently just not my outgoing emails. I would like to transfer my email but the other email i have is a proton email and they are a whole other headache. Please help.

OS: Linux / Android

TB Version: 156.0

Current Outgoing Server Setup:

Server Name: smtp-mail.outlook.com Port: 587 Connection Security: STARTTLS Auth Method: OAuth2 Username: *****@outlook.com

Having issues sending e-mails due to message: "e-mail not sent. Cannot connect to SMTP server 47.43.26.4 (47.43.26.4:587) connect error 10060" Requires 2-6 attempts to send. Also, problems with sending attached files, claiming to be too large.

Mozilla Thunderbird installed on new WINDOWS 11 laptop in May 2026 as an email client for BT MAIL. It has continued to function without issue until early September. At which point it became an issue with sending emails difficult and mostly impossible. When sending I have been prompted to enter my account password, sometimes this would be accepted, but often not as the outgoing email would fail to be sent. The reason given that Thunderbird could not connect to the outgoing BT MAIL SMTP server, even though none of these settings had been changed since installation using IMAP. However a connection test is always a positive result and a certificate is provided. As I write today i have been able to send and/or FWD a few emails, but have no confidence that this will be the case going forward. Last week I made a one off donation to Thunderbird and after rebooting the laptop, I was able to send messages, but only for that day ! The sending issue reappeared the next day.

I have been told by OZ lotteries that my emails are being soft bounced with the error "Email is not delivered because the mailbox is full or for other reasons". They suggested my email inbox is Full but that's not the case. Any suggestions as how I can fix this please?

One day after windows update, my thunderbird can't not download email from yahoo, microsoft, google..etc I tested the connection be fine but I can't recive any email

Hi Today, several emails that I have received, which I think were sent from an Outlook account, have, instead of what I would expect to see as the sender's address under correspondents, have Microsoft account team <account-security-noreply@accountprotection.microsoft.com> When I click on the email, I can see the genuine sender's address This has only happened today At least one of the emails that I received came from someone that I know uses Outlook Any ideas? Thanks

I have a BT Internet email account configured in Thunderbird using IMAP.

I'm experiencing a problem where some emails in the message list have no Correspondent/sender or Subject, and sometimes the displayed time is incorrect.

For example, a message-list entry showed 12:55, but when I opened it, the actual email was from 8 September. The email body itself was present and correct.

My Inbox contains approximately 7,782 messages and took several days to synchronise. I also have numerous archive folders.

I have already:

Checked the BT IMAP settings — mail.btinternet.com, port 993, SSL/TLS. Allowed the entire Inbox to finish synchronising. Used Repair Folder on the Inbox. Restarted Thunderbird. Restarted Windows. Changed the message list from Cards View to Table View.

The problem persists.

Importantly, the same BT mailbox displays correctly in both the BT Mail app and iOS Mail.

I also experienced a very similar problem previously in New Outlook: some newly received BT emails appeared as [Unknown] with (No subject). Removing and re-adding the BT IMAP account and repairing/resetting New Outlook did not resolve it.

Thunderbird is therefore the second desktop IMAP client in which I've experienced this type of problem, while BT's own mail app and iOS Mail display the messages correctly.

I don't want to create a new Thunderbird profile because the existing profile contains thousands of emails and took several days to synchronise.

Could this be an IMAP synchronisation/message-header/indexing issue between Thunderbird and BT Mail?

I can provide screenshots and any Thunderbird diagnostic information you need.

I am not able to send emails the last couple days. Any ideas on how to fix this? My incoming mail works fine, but when I try to send and email, reply or forward, it will not send.

Thanks!

I would like to setup Thunderbird as my email client.My email service is provided by Godaddy with an Outlook account. When I am at the incoming server settings, it has my domain name, not smtp.office365.com which I tried with both authentication options (below) and with my domain name, the protocol was IMAP. I changed the port from 143 to 993. I changed security from Autodetect to SSL/TLS. For authentication, there was not an OAuth2 option, I tried Autodetect and Normal password, neither worked. And I used my domain email password. with using my domain name, it came back with an error an suffixed my domain name with :110. It stated that this was not the correct domain and there was a security issue. It is not clear how I should progress.

rentitnow@mail.com was able to be accessed thru Thunderball. BrianKrantz@mail.com says wrong credentials. I know for sure the credentials are correct. They use the identical port. What can be done?

Hi, Last week, Thunderbird stopped receiving & sending emails with CenturyLink. I can access CenturyLink emails via their website and on my android.

Using Google, it said the configuration should be changed to CenturyLink's settings. It looks like Centurylink changed the settings for legacy email "centurytel.net". I went to CenturyLink website and copied their settings the best I could.

https://www.centurylink.com/home/help/internet/email/how-to-set-up-your-email-server-settings-to-go-through-pop-and-smtp.html

1. CenturyLink website shows changes to the following settings.

       a.	Incoming Server:  POP:  pop.centurylink.net    Port: 995, Security:  SSL
       b.	Outgoing Server:  SMTP:  smtp.centurylink.net    Port:   587     TLS if available
       c.	Username:  Full email address which for me ends with @centurytel.net

2. Thunderbird settings are: (screen print attached)

        Incoming:  POP: pop.centurytel.net  Port:  995, & Security:  SSL/TLS.  
        Outgoing SMTP:   Server:  smtpauth.centurytel.net    Port:  587,  & Security:  STARTTLS

I only changed the POP and SMTP server names. The security settings could not match up exactly since the drop down options did not have SSL and TLS individually. I left the original settings Thunderbird had of SSL/TLS for incoming and STARTTLS for outgoing. A screen print of Thunderbird's original settings is attached.

After following the settings configuration setup in Thunderbird, entering my correct password, I received this Authentication error: "Unable to log in at server. Probably wrong configuration, username or password." That's as far as I can go. Thank you for any help you can provide.

Mail sent to me as cc: and/or bcc: addressee (but not as a To: addressee) is received at my ISP mail account, but Thunderbird will not retrieve them.

This has been going for a long while it seems, but I don't get much mail addressed as cc: or bcc:, so I only recently became aware of it.

My ISP webmail interface uses Roundcube. Cc: and bcc: messages sent to me show up there. I have Thunderbird 156.0 installed on two macOS 27.0 machines and Thunderbird 24.0b2 installed on Android 17 (includes all updates through Android security update of September 5, 2026). Neither of the three will retrieve the cc: or bcc: messages, but all other e-mail functions work as expected.

My ISP says it's a Thunderbird problem, but I ain't so sure. Any ideas?

I have been receiving the error message quoting the SCO1 policy about reaching my sending limit every day recently. This has happened even when I have only sent 1 or 2 messages and these have only been to a handful of people.

"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.."

I have seen a previous strand where this was explained as being something imposed by the email provider not Thunderbird. However I have managed to send emails from the website of my email provider that I haven't been able to send through Thunderbird. This suggests that the previous answer was wrong. I would like to use Thunderbird so please help me sort this out.

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"?