problem with mail ettension and utf-8

I use the mail extension for the contact form.

My problem is that the mail is receiveing at windows mail of vista with broken the greek characters.

I made a die( $email->message); and the chars are ok.

I use xampp and mercury.

What may be wrong?

Outlook Express seems to have problem with UTF-8. I don’t know have to fix it other than using ISO-8859-?. IIRC, when I tested Outlook (not Express) worked as expected.