James Stephens

Remote images

It is a good idea to block the loading of remote images in the Privacy field under Tools –> Options –> Advanced:

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Spammers often put remote images in emails that, once loaded, pass your email address in the image tag back to a collecting site, thus validating the email address as real and increasing the chance that it will receive more spam immensely. The image does not have to be visible so without this protection from thunderbird you won’t even know that a remote image request was made.

Thankfully with the above option enabled, thunderbird will alert you when there are remote images:

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You won’t see the warning if the message has already been recognized as junk mail as the “Thunderbird thinks this message is junk mail” warning will appear in its place.

What’s new in v1.5?

Thunderbird 1.5 adds an additional couple of improvements to its spam filtering:

1. One now has the possbility to trust spam headers set by spamassassin or spampal:

   
   (click image to enlarge)

   This feature is not well documented. I am experimenting with having this feature enabled to trust headers from spamassassin and I have bayesian filtering turned off in spamassassin. In my experience the bayesian filtering in spamassassin is powerful, but requires constant training and if a message is mislearnt as ham or spam the filters have to be untrained and this is more compilcated than simply unchecking an icon as in thunderbird. By disabling the bayesian filtering in spamassasin and leaving its other useful features enabled, what spamassassin contributes to thunderbird is complementary to the bayesian learning that thunderbird is already very good at.

2. Thunderbird 1.5 recognizes certain characteristics of phishing email scams and will alert you if its suspects this is the case. Here is an example:

   
   (click image to enlarge)

   This feature works well, but note that you won’t see the warning if the message has already been recognized as junk mail as the “Thunderbird thinks this message is junk mail” warning will appear in its place.