thunderbird filter for "Content-Transfer-Encoding: base64"

I'm getting spam that has a consistent signature in the (raw) body of the text message (and it's only purpose is to obfuscate the text to get around filters. The common signature is:

Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: base64

Can I write a filter for this signature?

Thanks - Doug

Answer

Yes you can. Go to the Tools menu and select "Message Filters". Click on "new" and under "match all of the following" click on the select box that says "Subject" and select "Customise ..." and enter "Content-Type". Click "Add" and then OK.

Now in the select box you will have "Content-Type" as an option and you can make the condition "is" and put "text/html; charset=utf-8 Content-Transfer-Encoding: base64" in the text box.

However other emails will almost certainly have the same header, so you want to look for other things from the email that can narrow it down further. Maybe the User-Agent or something else.

And even once you've got a fairly narrow filter be sure to check your spam folder regularly for a while to see if you are catching any good emails.

Personally I've had a pretty good experience with just marking messages as spam and having Thunderbird learn to recognise the spam. To do this, go into "Account Settings", select "Junk Settings" and tick the box next to "Enable Adaptive junk mail controls for this account".