I want to create a folder "_Other" to hold unclassifed mail until I get enough to create a special folder for it. The leading underscore should cause it to sort to the start of the folder list. I try to keep Inbox empty. Thunderbird won't let me use this folder name. The Create button on the New Folder dialog stays greyed out. I'm able to do it with other clients. (I have the ancient Mulberry client as a backup.) I was able to create "-Other" with Tbird but it doesn't show up in the Tbird folder list. (Looking on the server from a shell login, I see Maildir/.-Other.)

This experiment suggests that Tbird treats certain leading characters in folder names as special. What are the hidden rules here?

SOLVED: PEBCAK. I failed to see the existing "_Other" folder sorted beneath the predefined folders like Inbox, Drafts, Sent, and Junk. I'd initially typed "Other" and then added the underscore and that's when Tbird greyed out the proposed new folder name. I misdiagnosed that as a special character, not a refusal to create an existing folder.

I have recently tried to make use of the Thunder AI feature to apply tags to my emails.
I connected it to Ollama and tried half a dozen different models: llama3.2, phi4-mini, mistral, qwen3.6 and several others.
I don't think the default prompt is very useful, but it sometimes yields reasonable results. But often the model doesn't follow the directive to create clean JSON and I get tags with comments in them or junk like that.
I spent a couple of hours trying to modify my prompt, especially by dumbing it down. At the end I just asked of the email-Address contains "Amazon" it should tag it with Amazon. It didn't even succeed to do that reliably.

If anybody has found a somewhat reliable combination of Ollama model with a prompt I would be very grateful as a base for further tries.

Sometimes I reply to an email when the subject of that email is not relevant. When I do this, I delete the subject line and the body and write them both from scratch. My reasons for doing this are:

1. Sometimes I find it easier to remember subjects than contacts, so finding a relevant email is quicker than finding the required contact.
2. Sometimes I want to email a group of people and finding a previous email on which they were all recipients is quicker than listing all the recipients on a fresh email.

When I did this on Gmail, which was my only mail client for many years, the email with the new subject would start a new conversation. On Thunderbird, the behaviour is different. The new email is part of the existing thread.

Is there a way to change the Thunderbird behaviour to be like Gmail, i.e. thread emails by reference until I change the subject, then start a new thread?

Just updated to TBird 150.x, and am very happy to see the option to sort the move to folder list alphabetically is available.

The MRU sort was horrible, IMO.

I am using the Thunderbird filters relatively extensively and have rule to forward message automatically on my behalf based on the sender's address.

It working mostly as expected but when the mail has a large attachment(s) (say a few Mb, nothing crazy) I often end up with the mail forwarded with a zero size attachment, which is rather annoying.

Exemple of forwarded mail with 0 size attachments

Anyone else seeing this ? Any suggestion for a fix ?

I've been using Mozilla Thunderbird on Linux for a couple of years now. Naturally, it is one of the first email clients many Linux users look at: open source, powerful, privacy-friendly, and independent from big tech ecosystems.

At first, I struggled a bit with the workflow compared to clients like Microsoft Outlook, especially around searching mails and some UI quirks. Over time, however, I got used to it and now i use for most of my mail tasks (professionally and private).

Yesterday I helped my wife set up Thunderbird on a new windows PC. During that process I noticed several small onboarding and usability issues that imo could and probably will easily discourage new users, especially people who are less technical and are simply looking for a smooth alternative to mainstream mail clients.

I wanted to share this as constructive feedback, but also include the solutions I found in case they help other users experiencing similar issues. Hopefully there are easier options for many "difficulties" we had.

1.Dark mode readability

Dark mode looks ok overall, but replying to emails can sometimes result in black text on a dark background, making messages unreadable.

This can usually be improved via:

Settings → Composition → uncheck “Use reader’s default colors”

However, disabling this also affects how dark mode behaves in the message body. Some views, such as advanced search results, also still seem have readability issues as well with black text on very dark backgrounds.

2.Signature setup feels more technical than expected

Thunderbird supports HTML signatures, which is powerful, but creating and editing them is not very intuitive compared to modern email clients with a built-in WYSIWYG editor.

The workaround I used was:

• create the signature inside a mail
• select the signature
• choose Insert → HTML
• copy the generated HTML
• enable HTML signatures in the account settings
• paste the HTML there

It works, but it is not an easy find for average users.

Than there was an automatic “--” separator added above signatures. This can be disabled via:

Settings → General → Config Editor
search for:

mail.identity.default.suppress_signature_separator

and set it to:
true.

Than, when replying to mails, the cursor always appeared under the signature. This can be changed via:

Account Settings → Composition & Addressing →
“When quoting, start my reply above the quote”

A bit weird that the default setting is to add text under the signature.

And finally there is no possibility it seems to add a signature afterwards to an email automatically with an "insert signature" function. There are add-ons for that, but than you seem to have to create the signature in a second place which does not give a polished impression and is dangerous for forgetting to update one of your signature versions.

3. Attachments are easy to miss

Attachments being displayed below the email body makes them surprisingly easy to overlook.

There is currently no simple built-in option to move them higher in the interface, but I managed to improve this with a custom CSS workaround found on reddit.

Steps:

• create a folder called: chrome inside the Thunderbird profile folder
• create a file called: userChrome.css
• add:

​

#attachmentView, #attachmentBar {
  order: -1 !important;
  background-color: blue !important;
}

Then enable custom stylesheets via:

Settings → General → Config Editor

search for:

toolkit.legacy.userProfileCustomizations.stylesheets

and set it to:
true

After restarting Thunderbird, attachments become much more visible. You can change blue in another color your prefer.

This works well, but it is definitely not something less technical users would easily discover and a bit weird that the user does not get the possibility to alter this location without having to customize css files (as under the body is not the most traditional location).

4. Sending mails feels slower than necessary

There is no incline mail editor like for example outlook which allows to reply on mails without opening a new tab or window but this is just getting used to i think.

However, when sending an email, Thunderbird shows a sending progress dialog for a few seconds. This quickly becomes very annoying when you want to reply or forward multiple emails quickly.

I later discovered this can be disabled via:

Settings → General → Config Editor

search for:

mailnews.show_send_progress

and set it to:
false

After that, sending happens smoothly in the background, which feels much more modern. But it makes you wonder why this is not a default setting?

6. Default email formatting

By default, pressing Enter creates paragraph spacing instead of a simple new line.

This can be changed via:

Settings → General → HTML Style

and unchecking:

“Use paragraph format instead of body text by default”

Again, easy once you know it exists, but probably confusing for first-time users.

7. Exchange / shared mailbox experience

Using Exchange through Owl for Exchange works reasonably well, but shared mailboxes can become visually cluttered.

Folders from shared mailboxes tend to blend into the main mailbox tree rather than clearly appearing as separate accounts like they do in most other email clients. For users managing multiple shared mailboxes, this can become confusing and messy quickly.

I also could not find an easy way to unsubscribe from certain shared folders like you often can with IMAP accounts.

Marking frequently used folders as Favorites however does help significantly.

Hello TB users, I've been a TB mail user for long years(on Linux and limitrd on Windows). To reduce exposure to G***** and its known/unknown connections I would like to use TB calendar and tasks across my family members. After looking how I could use CalDAV(a server on RPI) syncing I'm looking now at the Android side. How could I sync TB calendar to android as that is our main 'gate' to enter events and tasks. Unfortunately Proton does not seem to have an option at this time. Would be nice if there is something available TIA

I can't seem to find this answer and apologies if it's obvious. How do I search by sender? When I use global search for a specific person (using their email address) it gives me every email that has their email address in it. And if I select that person from the people filter on the left menu of the search results nothing changes. The quick filter menu at the top of my inbox (ctrl + shift + k) doesn't have a sender option (just unread, starred, people in address book, tags, and attachments). There must be a way to search for emails just from a specific person. I'm using Thunderbird 150.0.2 (auto updates). Thanks for your help!

When downloading many emails to ".eml" files using Thunderbird, the downloading is interrupted if one email has an excessively long subject name.

Every time this happens, the email that causes it has to be located manually. This makes exporting a high number of emails impractical.

Is there any way to save all emails as ".eml" without being interrupted by excessively long file names?

Lovin Thunderbird and the Message filter which allows instant nuking of all spam. But im looking to make it a bit more efficient and block many more before they come. A lot of trash has trash top domains like .club .shop .biz .w etc.

How does one, if one can, create a whitelist that only allows a few top domains? Nuking everything that doesnt come from .se .com .eu .jp etc.?

If one makes a new folder and move approved mail there, the spam remains in the first one without getting nuked. Does Thunderbird not have a whitelist function? Or does one have to make three filters? Classify all incoming mail as junk - classify top domains as not junk and move them - run spamfilter with spam keywords on new folder. Delete all mail marked as junk.

But how does one guarantee the filters run in sequential order so it doesnt just delete all incoming mail? Feels like an actual whitelist function is missing.

I have an IMAP account with 37 GB (about 20000 inbox and 7500 sent) on thunderbird last ESR version shared between 3 computers.

Some days ago it has become extremely slow on all computers. Emails appear in the list, but when I try to open them, the screen stays blank for several minutes until it finally opens. Also, while sending, it takes a long time to copy the message to the Sent folder.

The activity manager shows it is 'bringing up to date' the Inbox, Sent, and Archive folders. It seems to finish after several hours, but whenever I close Thunderbird and reopen it, the process starts all over again.

What I did so far:

• I create archive folders by year for old emails in order to have less mails in folders
• Under gmail settings, tags, I hide on IMAP gmail default tags (starred, important, scheduled)
• I even create a new profile

What can I do? Anyone else has this problem?

Many users wonder why admin experts like us do not directly use Thunderbird (the email client) to import MBOX files into Office 365 applications. Here are limitations of migrating MBOX to Office 365 using Thunderbird: 

• Thunderbird even up to the latest version is only compatible with exchange-online accounts and not on-premise ones. 
• Although Thunderbird stores email in MBOX format (maildir also) there is no native way to import MBOX - in most cases users depend upon ImportExport NG Tool which is a free add-on and not 100% reliable.  In situations where a user migrates company level data (which is mostly the case with Office 365 account. It is not feasible.
• Although Thunderbird does not have a mailbox size, using Thunderbird to migrate MBOX to Office 365 involves creating multiple copies of the same data which takes up storage space. 
• Although Thunderbird is a great free mail client it is not a migration tool there is no guarantee that the email attachments, folder hierarchy is preserved - which is important to most users.  
• Thunderbird is one such application which is known for its crashes - a crash or a profile corruption can lead to data loss which can be risky. 
• Another disadvantage is the time taken by Thunderbird.

In short you are trying to fit a square peg into a round hole. Thunderbird is not bad, it is just that it wasn't designed for it.

https://preview.redd.it/6ab3ifvnh11h1.png?width=1536&format=png&auto=webp&s=1d5406e08e1983332a7b09b4d0988a0da743057e

I simply follow the standard procedure, add my password in the web page that opens (OAuth).

But then, I get "authentication error".

The password is correct because I can properly connect to Outlook on e.g. Firefox.

Known issue ? Any fix ?

Hello all!

With Thunderbird 150.0 (Fedora Linux) I seem to have lost the ability to sync with my outlook.com calendar. TBSync is not compatiable with this version of Thunderbird. Is there an alternative to this or will I just have to wait for an updated version of TBSync.

Thank you!