The State of ThunderBayes

First, let me say that I am very sorry for neglecting this space for so long. I’ve been busy with real life and some other projects that will may show up here sometime in the future.

Yes, I’m mostly ignoring the comments on the ThunderBayes posts these days due to a lack of time to even do everything I want to do, let alone what other people want me to do. To be truthful, I don’t even use ThunderBayes anymore because all of my email accounts have been switched to gmail and the spam filtering there is Good Enough for now. That is not to say that ThunderBayes did not work for me when I did use it (it did everything I wanted it to do, and even did a good job at that). However, ThunderBayes is a bit of a kludge and certain parts of it need to be rewritten to be more usable by the average, non-hacker user. Unfortunately I do not have the time nor the will to fix it at this point. If someone else wants to pick up the project I’d be willing to talk (email me).

I do hope some people can still get some use out of the add-on, but at this point I am declaring it unsupported by me. Maybe I will find time sometime in the future to do more work on it, but don’t hold your breath. Others are free to share their solutions to problems of course. Ideally a forum should be setup somewhere because blog comments are not a good place have support discussions, so please refrain from doing that here. Does the Mozilla add-ons site have any type of forum or Q/A section for the community to provide support?

To those of you who are still brave enough to try it out, I would encourage you to first try the default setup with the internal SpamBayes filter. If that does not work, try installing and configuring SpamBayes separately and use the ThunderBayes Add-On options to make ThunderBayes talk to that manually installed copy of SpamBayes. I know that sounds ugly, but it might help some people to continue to use the extension even if it has a few flaws. (Most of the recent problems have been related to the internal SpamBayes config.)

With sincere regrets for not being able to answer every question and fix every problem related to ThunderBayes, I wish everyone who tries it out all the best.


ThunderBayes 1.0.1

This is a bugfix release. I apologize to anyone who was confused because version 1.0 did not save the ThunderBayes settings. One never can do too much testing when developing software.

Download ThunderBayes 1.0.1

ThunderBayes 1.0

SpamBayes integration for Thunderbird.

UPDATE: ThunderBayes 1.0.1 is now available.

Download ThunderBayes 1.0


ThunderBayes provides a toolbar button similar to Thunderbird’s Junk button with which email can be classified as Spam or Ham. Clicking the button causes two things to happen: (1) it sends the source of the selected messages to SpamBayes to be classified and (2) it optionally moves the messages to a folder of your choice (this can be configured in the extension options). It includes a custom version of SpamBayes, and provides a simple preference page in the Thunderbird Account Settings where the SpamBayes POP3 proxy and message filters can be configured.

Changes in this version

  • Added integrated SpamBayes proxy server (can be disabled/bypassed).
  • Added ThunderBayes configuration in Thunderbird Account Settings (POP3 accounts only).
  • Implemented REST API for SpamBayes, which allows more efficient training and automatically updates the SpamBayes review page when training in Thunderbird.


ThunderBayes 1.0rc4

Better support for Thunderbird 1.5 this time.

Download ThunderBayes 1.0rc4

ThunderBayes 1.0rc3

Some more minor bug fixes:

  • Re-implemented save routine in ThunderBayes Account Settings to respect the Cancel button after switching away from the ThunderBayes prefs page.
  • ThunderBayes now recognizes localhost and as being the same host name.
  • The prefs page now displays the proxy host/port in addition to the real server/port.
  • Updated migration guide to include note about privileged ports for Unix users.

Download ThunderBayes 1.0rc3

ThunderBayes 1.0rc2

Fixed annoyance: the embedded SpamBayes/Python executable for Windows popped up a console window each time Thunderbird was launched.

Download ThunderBayes 1.0rc2

ThunderBayes 1.0rc1

Well, it’s finally (almost) happened. ThunderBayes has reached the 1.0 milestone!

Download ThunderBayes 1.0rc1 now and give it a try.

NOTE: for those already using ThunderBayes, please read the migration instructions before installing the new version.

This is a huge usability milestone. ThunderBayes now takes care of all the dirty work involved in installing and configuring SpamBayes, and it even makes it very simple to configure filters to move unsure/spam messages to folders of your choice. These new features are integrated into the Thunderbird Account Settings dialog, so you can configure ThunderBayes for each account at the intuitive place, with all the other account settings. Under the covers ThunderBayes also uses a new training API that allows more efficient training.


ThunderBayes 0.2.2

Very small update here. It appears that the nsICustomColumnHandler interface changed between Thunderbird 2.0b2 and (a getRowProperties() method was added). Thanks to Kevin Yank for pointing this out!

In plain English: it was a minor issue. Your error console will have less junk in it now.

Download: ThunderBayes 0.2.2

ThunderBayes 0.2

ThunderBayes – integrate SpamBayes into Thunderbird.

Update: works with Thunderbird 2.0.0.* as of 04/11/2007.

Download ThunderBayes 0.2.1

New features in this version:

  • Improved the toolbar button to allow messages to be marked as ham or spam regardless of the actual spam status of the message.
  • Added “Move on mark as ham” feature, which moves messages to Local Folders Inbox by default (the folder can be customized in the ThunderBayes extension options).
  • Added two new columns to the message list (Thunderbird 2.0 only):
    1. Spam Status – a column that shows spam status with four icons:
      • Spam – red circle with slash
      • Unsure – yellow question mark
      • Ham – gray dot
      • Unknown – gray question mark (this means the message did not have a “X-Spambayes-Classification” header, which probably means it did not pass through the SpamBayes proxy)
    2. Spam Probability – a column that shows the spam probability as a percentage (0% is ham, 100% is spam). Note that this column will be blank for messages that were received before ThunderBayes 0.2 was installed.
  • Added a new “unsure” button state to the toolbar button.
  • Improved spam status recognition. ThunderBayes now uses the X-SpamBayes-Classification header to determine the spam status. In the past it relied on the junk status which was set using a filter.
  • Thunderbird 2.0 compatibility.

Send bug reports and feature requests to . Include the word “ThunderBayes” in the subject line.


ThunderBayes 0.1.1

Download the latest version from the Extension Mirror (I’m still waiting for it to be approved on Mozilla Update).

This release is a minimal update: ThunderBayes how displays a progress bar while messages are being processed.

However, I will note that I am very pleased with the results of using the extension. Before I started using ThunderBayes I got 10 to 15 spam emails in my inbox per day. Now I get one or two! All due to a simple and convenient method of training SpamBayes.