Mails don’t send when using Greek characters in Subject field.

Hi there,

I get an error when I try to send an email and the Subject in the contact form has been entered in Greek alphabet.
When I switch the Subject to Latin alphabet the contact form works perfect.

Thou, I can use Greek in the Name field or the Message field, without any problem.
The conflict is only in the Subject field.

Can somebody help?

Thanks,
V.

The page I need help with: [log in to see the link]