Contact Form 7 accented characters replacement in mails

Hello,

i am using WP 4.2.2 and cf7 and in the mails i receive all accented characters are replaced by ?. The rest of the text is ok. My language is greek and i use Shopkeeper theme. I found other posts with similar problems but none of the solutions applies to my problem.

My web site is blackribbon.gr

Any help would be appreciated.

Thank you.