Thunderbird Community Forum

Hello Thunderbird Support,

I am using Thunderbird with an email account hosted by Webhosting UK (webhosting.uk.com).

I am experiencing an issue where legitimate emails, including booking notifications, are repeatedly moved to the Spam/Junk folder.

When I mark these messages as "Not Spam" and move them to the Inbox, they return to the Spam folder after some time.

I have already checked with my hosting provider and confirmed that the issue is not related to the hosting service.

Could you please provide a Thunderbird configuration guide or help me understand the correct settings to prevent legitimate emails from being repeatedly moved to the Spam/Junk folder?

I would appreciate step-by-step instructions on how to resolve this issue permanently.

Thank you for your assistance.

I am trying to send an S/MIME encrypted email from Thunderbird to:

jobcenter-chemnitz.netzwerkpartner@jobcenter-ge.de

The recipient certificate is provided by the official certificate directory of the German Federal Employment Agency (Bundesagentur für Arbeit).

I downloaded the recipient certificate and successfully imported it into Thunderbird under:

Settings → Privacy & Security → Certificates → Manage Certificates → People

The certificate is displayed correctly there. The email address contained in the certificate is:

jobcenter-chemnitz.netzwerkpartner@jobcenter-ge.de

The certificate is valid from July 29, 2026 to July 29, 2028 and includes E-mail Protection and Key Encipherment.

The required CA certificates are also installed:

BA-Class-1-Root-CA-4:PN BA-VPS-CA-11:PN

However, when I compose an encrypted email to this exact address, Thunderbird reports:

“You have selected to encrypt this message, but the application failed to find an encryption certificate for jobcenter-chemnitz.netzwerkpartner@jobcenter-ge.de.”

Under S/MIME → Recipient Certificates, Thunderbird also shows the certificate as “Not found”.

I have already tried:

deleting and re-importing the recipient certificate completely restarting Thunderbird after importing it manually typing the recipient address in lowercase without using autocomplete checking the complete CA certificate chain temporarily disabling OCSP

None of these changed the result.

My own personal S/MIME certificate works correctly. As a test, I can compose an encrypted email to my own email address without any certificate error. Therefore, the basic S/MIME configuration and my own certificate appear to be working.

When I reproduce the problem with the Thunderbird Error Console open, I get:

NS_ERROR_ILLEGAL_VALUE (0x80070057)

related to:

nsIMsgComposeSecure.beginCryptoEncapsulation

This seems similar to Mozilla Bug 2021265, where a manually imported recipient certificate is visible in Certificate Manager but is not found when composing an encrypted message.

Is this a known issue in Thunderbird 140 ESR, and is there a workaround for using this manually imported recipient certificate?

I have three email accounts in thunderbird, each using unique domain names. I connect through a ProtonMail Bridge to my Proton account which is also configured with the three domains I'm using. Proton recognizes all three as configured correctly and if I send from any one domains address, all domain addresses receive it.

It appears things have gotten corrupted when I was doing lots of configuring and all my email inboxes share the same contents even though Settings->Server Settings->Local Directory is pointing to separate unique directories (the original ones) for each account.

Also, the "Drafts, Sent, Archives, Junk, Trash, and Outbox" folders are gone for all three inboxes (but exist for "Local Folders". The only "folder" under each account is "Inbox", and all three accounts (e.g. larry@a.com, curly@b.com, and mo@c.com) all have the same contents where every email from every account is all in the same Inbox. They're all mixed up.

I've not a clue what went wrong other than Thunderbird doesn't handle configurations well. I've tried the Inbox->Properties->Repair Folder to no avail. In fact, when I did that, it appears to have downloaded my main accounts inbox into the other inboxes possibly resulting in the mixup of email.

Thoughts?

I am using Thunderbird 140.15.0esr and have noticed that my Ashampoo Backup is not able to store my Thunderbirs files any more. I have looked up how to find the Thunderbird files and the posts mainly say :

C:\Users\<YourUsername>\AppData\Roaming\Thunderbird\Profiles\

But when I follow this path there is no Thunderbird folder in Roaming as shown in the attached screen shot

Can you help please.

Ian Hulley

As the title says, over the last two days Thunderbird won't do SMTP authentication to Outlook. It has worked happily for years and nothing at my end has changed.

I've the latest version of Thunderbird - 140.15.0esr (64-bit) - and this is Windows 11. It works happily from the Outlook desktop so the password is correct.

The authentication method is OAth2 and connection security is STARTTLS. Server is smtp.office365.com and port 587.

Anyone else having issues? Presumably MS have changed something (again)

Has anyone any suggestions on how to resolve?

I have several Yahoo accounts set up in Thunderbird, but I get this frequent (several times a day) error notification from just one:

"The current operation on 'Inbox' did not succeed. The mail server for account Yahoo (xxxxxxx) responded: p."

I'm sure this is a truncation of the complete error message. How can I see the complete message?

There seems to be no consequence of the "error" - everything appears to work as normal. It's just annoying.

Afrihost is my service provider and emails are accessed via a webmail page. The size and functionality is limited and I use Mozilla Thunderbird on my laptop with Windows 11 to save emails in local folders on my hard drive. I can't do this via webmail and my backup changes between Thunderbird and the webmail page. Yesterday I cleared my inbox to local folders in Thunderbird but am no longer receiving emails there. My old and new emails can still be seen in the webmail inbox, I don't know if I've exceeded some limit and I don't want to lose old emails in my local folders. Personal, low volume use only