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For 3 days, I haven't been able to access my GMX email account. It tells me every time "Login to the server imap.gmx.com with username '[edited from public] @gmx.com' failed. I hadn't changed anything beforehand and all the entered data is correct. My other accounts like gmail, yahoo, works just fine. Tried installing older versions and still no success. Outlook app works fine either. I'm pretty sure that GMX mail server made some changes that Thunderbird is missing. Please verify.

Best regards

Nilson Xavier

I am getting an error for an outdated certificate on my mail smtp server and when I try to add a security exception Thunderbird does absolutely nothing when i click the button to add a security exception where I can send mail. I end up having to cancel the window and discard my email. It will also not go view the certificate and if you ask it to check it just hangs up forever in and endless loop of checking.

Hi,

I’m using Thunderbird on Windows and recently ran into a certificate warning that I can’t safely interpret, even after searching the web and using AI tools (which gave me inconsistent answers).

Thunderbird tries to connect to the iCloud contacts server p123-contacts.icloud.com (CardDAV). When it does, I get a “wrong site” certificate error. When I click “View certificate”, Thunderbird shows a valid certificate, but not for Apple/iCloud – it’s for login.kraftcom.de (issued by DigiCert / GeoTrust TLS RSA CA G1). I did not accept the exception.

From what I can see online, p123-contacts.icloud.com is a legitimate Apple domain, but it is also mentioned in some phishing / scareware contexts, which makes me even more unsure how to interpret this combination (Apple host + Kraftcom certificate). I’m also not sure whether this is simply a captive-portal / ISP login interception effect or something that should worry the wider community.

My questions:

Is this behavior expected in any scenario, or does it indicate a misconfiguration / MITM situation that Thunderbird should treat as a serious security issue?

Is there anything I should check or change on my side (Thunderbird config, network, ISP, certificates)?

Is there any additional diagnostic information I can provide (logs, screenshots) that would help you assess whether this is a Thunderbird issue or a network/ISP issue?

I specifically did not confirm the certificate exception and I would like to keep my setup secure, but I also want to make sure the community is aware if this is a broader problem.

Thanks in advance for any guidance

I have been using Thunderbird for many years, and it's been a while since I cleaned out my Inbox & Folders. I get about 1200 emails a week, so the clutter is extreme. Yet it is still stable, and now I am waiting to see at what level it falls over. Currently I have 84,544 emails in my Inbox, 131,597 in the Junk Folder,33,718 in Archives, 13,388 in another Inbox, and a whole heap which get deleted when I compact the system.

I reckon compacting it has got rid of another 200,000 or so this year.

I am very impressed, well done guys.

[edited email from public support forum]

I just opened my Thunderbird e-mail account, did thunderbid only access emails from my sbcglobal account email account or did TB download the the 100,000+ SBCglobal emails to a thunderbird file that I can continure to access?. I believe that AT&T is going to delete my sbcglobal email account as I have canceled my AT&T internet service. I see sbcglobal messages in thunderbird that go back to 2008 that I would like to read again. Will these messages disapper when AT&T disables the SBCglobal email account.

Today in two of my accounts I get error message "Unable to open the summary file for Inbox on imapML. Perhaps there was an error on disk, or the full path is too long." Two other accounts work fine so no error on disk, and full path hasn't changed.

Hi-

I had this working then it magically stopped about a year ago and I can't get it back. When I try to open a pdf I get "...could not be opened, because an unknown error occurred. Try saving to disk first and then opening the file."

I have gone into settings and re-selected adobe acrobat and restarted but still can't open.

I am on a mac.

Thanks for your help! Crazy frustrating and time wasting issue.

I saw where there was a same problem liste a couple of months ago but the solution did nto work. As of this morning I can no longer send with my CompuServe Account. There was no change in my settings, and I have had the account in place with Thunderbird for years. I get an error to enter my password again, I do, then no luck. It asks again. When I cancel, I get an alert, sending of the message failed, Unable to authenticate Outgoing Server (SMTP), please check the password and verify the "Authentication method" in "Account Settings|Outgoing Server (SMTP)

I tried change the password authentication from normal to OAuth2. No luck.

No problem with downloading messages; they all come through.

I saved the message to be sent in my Draft Folder and then when going to the web version of CompuServe (really AOL and really Yahoo), my message is saved in the Draft Folder and I can then send it.

Thank you in advance.

Sal

When clicking any hot link in an email, whether FB or a web retailer email, etc. this message pops up: "This file does not have an app associated with it for performing this action. Please install an app, or if one is already installed, create and association in the Default App Settings page."

At a loss for a solution here. Can someone please help. Thanks.

When someone sends me a msg, it displays along with the HTTP equivalent? Trying to figure out what setting is out of Wack such that I ses the HTTPS display of the message? Thanks

When I use Mail Merge to generate emails for many recipients, they are put in the "Outbox", but Thunderbird will only send 10 emails at a time. After 10 emails, I have to close the program and start it again to get the next 10 sent. So to send 100 emails, the program has to be closed and started 10 times!

I have a problem with thunderbird. I can't fetch the certificate in my account settings, it seems it's not security approved. Normally when I type "fetch certificate" a window pops up asking me to confirm a security exception, but this function no longer works on thunderbird. Is there another way I can confirm the security exception?

I'm running Thunderbird 140.5.0esr (32-bit) on Windows 10 Pro Build 19045. After the last few updates the columns in the email listings are changing widths from what I've set them, this seems to happen after I close then reopen Thunderbird; which I'm having to do more often these days to resolve weird calendar malfunctions. For instance, the data column would appear so narrow that only the month/day show with "..." at the end, when I know I've looked at this yesterday with the full view of the date and time showing. I've reviewed my options and I've set them individually, set them globally and it makes no difference. Of course I've rebooted, etc. I have over a hundred local folders and they all change differently, of course some look the same but others don't. Most have the same column headings selected but it doesn't seem to matter. Some have the "Correspondents" column selected but many don't.

This is very irritating and I'd like to know why Thunderbird is doing this, and more importantly, how can I prevent this behavior in the future. Thanks,

Hello,

I've used Thunderbird for my e-mail for approximately 15 years, and now I can't currently send e-mail. I've gone through all the troubleshooting steps and also had Geek Squad attempt to fix it, but I'm still unable to send e-mail (I can receive them).

I've changed my password multiple times, reinstalled a fresh copy of Thunderbird on my Windows 11 laptop, restored the default settings for the outgoing server to align with what Verizon has specified, and nothing resolves the problem.

I keep getting the message: " Sending of the message failed. An error occurred while sending mail. The mail server responded: Email rejected. Please verify that your email address is correct in your account settings and try again."

Please let me know what the next step is so that I can use Thunderbird to send and receive my e-mails, like I have in the past.

Just opened TB. There were 8 or 10 emails. Went to another app for a few seconds. Went back to TB. Emails were gone. Have NO idea what happened. Know of any way to get them back or where they went?