Mail replies to myself

Dunno what happened, but now when I want to reply to mails I received from others, Mail wants to send it to my own mail address.

In Mail it looks like this:

From: 'Name' of the person who send the email

To: 'Adress of those that received the email (as well)

Reply (or Answer in Dutch) to: 'my mail address '

I just want to reply to the sender or to all recipients. But Mail puts my address in the 'To:' box.

How do I change this?