E-mail subject itself is header and headers must contain only ASCII characters. This is why UTF-8 (or any other non-ASCII charset) subject must be encoded.
Subject: Encoding problem: Date: Wed, 19 Jul 2006 14:50:30 GMT: I use filter in web.xml with UTF-8 enconde, but the resulted file of web.xmlisn´t in UTF-8.
This way of encoding non-ASCII characters in to ASCII is described in RFC 1342. Basically, encoded subject has (as you've already listed in your examples) following format: =?charset?encoding?encoded-text?= Based on encoding value is encoded-text decoded either as quoted-printable (Q) or as base64 (B). To get human readable form you need to pass encoded-text portion of subject header value to program that decode it. I believe there are some standalone commands to do that (uudecode), but I prefer to use Perl one-liners: For quoted-printable: perl -pe 'use MIME::QuotedPrint; $=MIME::QuotedPrint::decode($);' and for base64: perl -pe 'use MIME::Base64; $=MIME::Base64::decode($);' Be sure you pass only encoded-text portion and not whole subject header value.
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'.