KMail doesn't apply a filter with euro sign
 

I'm trying to create a filter on subject for incoming German emails

My regex looks so: \b([Bb]erufsunfähig.*|€)\b

(\b is word delimiter)

But it doesn't work for emails containing an euro sign in their subjects. First I thought that it should have something to do with unicode. But this part of regex \b[Bb]erufsunfähig.* work (contains a-umlaut), so unicode cannot be the cause of the problem.

ISO-8859-1 (Latin 1) did not include the euro, but does include other common unicode characters. It was added in the replacement ISO-8859-15 (Latin 9). Most likely the mail is using the old encoding; lots of software does. Check the headers for the character encoding. Here's one in my inbox:

Note character set encoding is windows-1252, which is Latin-1 with the addition of the euro and a few other characters.

What I've seen in the email source is:

The subject of the email is:
Of course I can create multiple filters as a workaround but it would still be interesting how to insert the euro sign into an existing regular expression with lots of logical ORs (|)

I have tried it with € and with \u20AC with no luck.