Being so sick of spammers trying to bypass text-based anti-spam filters by sending text as images (so-called “image spam”), I googled and happened to find an interesting website which explains how to set filters in Thunderbird to sort out that kind of junk mails (see the link below).

In addition to that, I created a new folder Possible Image Spam as a subfolder of Junk where such mails are stored, so that I can easily sort out “false positives”.

Note:
You should also set From to isn’t in my address book as decribed in the MozillaZine Knowledge Base.

• Stopping Image Spam In Thunderbird:
  www.neilturner.me.uk/2006/Aug/06/stopping_image_spam_in_th.html