I think that it is not comfortable to teach anti-spam without using Outlook. It is exist only one way - writing an e-mail address in to the white or black list. The way to the white list is too long. It wold be better to see a list of letters and check if it is spam on not. What do you think?
The extra functionality of the antispam toolbar is only available for Outlook (not Outlook Express) at this time. There is no generic way of writing a plugin that would work in every mail client, which is why we do it for the most widely used one only. We might add plugins for other clients in future if the demand for it justifies the effort.
Probably 95 pct or more of incoming spam is intercepted and quarantined by my ISP’s filters before I even see them. My mailer is Thunderbird, which has the ability to “learn” what you do or don’t consider junk, so it’s extremely rare to see spam in my (mailer’s) inbox, maybe once every 2 or 3 months.
Given that the two stages of filtering work quite well, I can happily live without avast’s anti-spam function (I’ve got the free version anyway).
I’m agree at all. But it is possible a general solution is realized in Avira. There is a dialog showing all e-mail passed through anti-spam and you can mark all emails are junk or not junk in it. It is the very general solution and you don’t need to do any plugins. 
Is it possible to setup AIS 5 to mark as a spam for example all messages that are written in English? (I only want to receive Polish messages).
No, afaik…!
asyn
;D 
…okay seriously you can almost do that with windows live mail, by banning domains by country…problem is immigration, what if a Polish mails you from Italy ???
spamfighter can filter spam by language ( not the free version i think )
And the program is in 21 languages ( see flag in top right corner )
http://www.spamfighter.com/